Re: [Help] How to Replace File Operations in File System?

2014-02-20 Thread Valdis . Kletnieks
On Thu, 20 Feb 2014 17:48:07 +0800, freeman said: However as I planed it, I don't want involve the user too much- just to keep simple. I plan to build a safe box, and people throw personal things into it. That's all. The first question is - what are you trying to protect against? The answer

Re: Side effects of open system call

2014-02-20 Thread Valdis . Kletnieks
On Thu, 20 Feb 2014 20:36:44 +0530, Rahul Bedarkar said: Often the open(2) call has unwanted side effects, that can be avoided under Linux by giving it the O_NONBLOCK flag. I have seen open man page but can't find what are side effects of open. Well, for starters, the open() call can

Re: How to test my patches before submitting them to LKML?

2014-02-07 Thread Valdis . Kletnieks
On Fri, 07 Feb 2014 16:31:04 +0100, Matthias Beyer said: I'm currently working on some stylefix-patches for drivers/cdrom/cdrom.c and I'm slowly getting to a point where they seem to be ready. How to test my patches? Note that some maintainers don't like accepting style fix patches, because

Re: How to test my patches before submitting them to LKML?

2014-02-07 Thread Valdis . Kletnieks
On Fri, 07 Feb 2014 12:51:42 -0800, Arlie Stephens said: Personally, I have 2 goals: - get paid - get good enough at linux to successfully play in the core kernel (successful == get changes accepted routinely, etc. etc.) Doing the former mostly just requires finding the right upstream

Re: 16-Byte aligned memory allocated in user space and then

2014-02-05 Thread Valdis . Kletnieks
On Wed, 05 Feb 2014 11:35:27 -0800, m silverstri said: If I allocated memory in user space and make it 16 byte aligned memory, and then pass it to kernel and setup DMA for my kernel driver, will my kernel driver still see the memory in 16-Byte aligned memory? The hard that my kernel driver

Re: malloc memory to be 32 byte aligned in kernel

2014-01-28 Thread Valdis . Kletnieks
On Tue, 28 Jan 2014 17:00:13 -0800, m silverstri said: Thanks. How big should be my slab cache and how to allocate from that? kmem_cache_alloc() and kmem_cache_free() are your friends. And to declare a struct ' __attribute__(aligned(32))'', does that mean I do that for every file in my

Re: Where is the version.h?

2014-01-27 Thread Valdis . Kletnieks
On Mon, 27 Jan 2014 10:05:05 +0800, parmenides said: According to LDD3, the linux/module.h automatically includes the linux/version, which define some macros to help test the kernel version. But I search the source tree, and can not find version.h in include/linux. Where can I find it? It's

Re: make kernel driver closed

2014-01-27 Thread Valdis . Kletnieks
On Mon, 27 Jan 2014 17:19:46 +, Jeff Haran said: There are lots of companies with closed source Linux drivers. My former employer Brocade Communications Systems wrote, maintained and shipped their Fiberchannel stack Linux drivers consisting of tens of thousands of lines of closed source

Re: Where is the version.h?

2014-01-27 Thread Valdis . Kletnieks
On Tue, 28 Jan 2014 02:57:51 +0800, parmenides said: Accroding to LDD3, version.h is included with the path linux/version.h, therefore I think the include/generated/uapi/linux/version.h might be symbolic linked to include/linux/version.h during compilation. Is this the

Re: How to use memcpy in kernel driver

2014-01-27 Thread Valdis . Kletnieks
On Mon, 27 Jan 2014 11:53:00 -0800, m silverstri said: I try #include stdio.h Can you please help me? stdio is a libc invention, only used in userspace. As such, you can't call anything in a shared library from within kernel code (although there are similarly named routines for many things).

Re: Looking to dissect kbuild

2014-01-27 Thread Valdis . Kletnieks
On Mon, 27 Jan 2014 12:49:40 -0800, Eric Fowler said: I want to know more about how that file interacts with the build system. In particular, in situations like a build seeing a syntax error in foo.c, I want to trace from foo.c all the way up to every entry in dot-config that imports or

Re: make kernel driver closed

2014-01-25 Thread Valdis . Kletnieks
On Sat, 25 Jan 2014 15:43:19 +0200, Alexandru Juncu said: That is not true. Technically speaking, you could do that. Think of drivers from vmware or nvidia. The only reason NVidia gets away with it is because it's not actually a Linux driver. To save Phani the trouble, I'll point at this

Re: What's the meaning of CONFIG_BROKEN_ON_SMP?

2014-01-24 Thread Valdis . Kletnieks
On Fri, 24 Jan 2014 17:43:35 +0800, parmenides said: CONFIG_BROKEN_ON_SMP: should be set in the kernel configuration, but isn't. I wonder what the meaning of the configuration is. How does it work? Thx! Drivers (and all other kernel-mode code, actually) need to do proper locking, so that if

Re: tcp packet split

2014-01-19 Thread Valdis . Kletnieks
On Sun, Jan 19, 2014 at 2:31 AM, net.study@gmail.com wrote: And why it is possible for one packet to contain uncontinuous part of different user protocol packets? Whatever gave you the idea that's possible? There's absolutely zero provision in the Internet standards for one packet to

Re: Issue compiling Kernel Module

2014-01-08 Thread Valdis . Kletnieks
On Thu, 09 Jan 2014 03:00:11 +0530, Arun M Kumar said: all: make -C /home/arun/Linux_Source M=`pwd` The directory the -C parameter points at has to be a Linux source tree that has had at least a 'make prepare' run inside it. In addition, to actually *use* the module, you'll need to

Re: simple memory malloc and free in ip_output.c

2014-01-01 Thread Valdis . Kletnieks
On Thu, 02 Jan 2014 12:12:49 +0700, Mulyadi Santosa said: Other than what others have said, IMHO it is better to avoid such rapid alloc/free, assuming your code fragment is running on every packet reception/sending. Instead, I suggest to allocate the memory before the ip_queue_xmit and

Re: Can't cleanly unload driver

2013-12-27 Thread Valdis . Kletnieks
On Fri, 27 Dec 2013 16:10:43 -0800, Eric Fowler said: I have checked that and the problem persists. I see insmod and rmmod - but no lsmod output. Not ls, lsmod. Different command. pgpfvNecn4jea.pgp Description: PGP signature ___ Kernelnewbies

Re: Can't cleanly unload driver

2013-12-27 Thread Valdis . Kletnieks
On Fri, 27 Dec 2013 19:33:50 -0800, Eric Fowler said: I suspect I am doing something wrong in the code with register/unregister_chrdev(), but I have been over that code a million times. It looks fine. Now: insmod the device, OK rmmod the device, OK Check /proc/devices , device # is

Re: Can't cleanly unload driver

2013-12-26 Thread Valdis . Kletnieks
On Thu, 26 Dec 2013 17:50:52 -0800, Eric Fowler said: I did an insmod ./mydriver.ko But rmmod reports Module mydriver is not currently loaded. But it is in /proc/devices: 248 mydriver Trying to reload it gives: insmod ./mydriver.ko Could not insert module mydriver.ko: File exists. Out

Re: how to find kernel patch applied on existing build kernel

2013-12-25 Thread Valdis . Kletnieks
On Wed, 25 Dec 2013 11:28:35 +0800, Dong Zhu said: rpm -q kernel --changelog That won't actually list all the 10,000+ commits between kernel releases - it often won't even list all the vendor-applied patches that they've put on top of the Linus kernel. And it assumes an RPM based system

Re: Query regarding physically discontiguous memory

2013-12-25 Thread Valdis . Kletnieks
On Wed, 25 Dec 2013 14:45:01 +0530, Pritam Bankar said: This is what I don't understand what does it mean by containing large holes? physical discontiguous memory? Is it like when I put 2 RAM chips in a system then memory for them will be discontiguous? Per my understanding RAM memory

Re: Linux-wireless: why use macro to call functions

2013-12-24 Thread Valdis . Kletnieks
On Tue, 24 Dec 2013 14:48:33 +0100, Adrian Ratnapala said: So the main (or only?) purpose of the macro is to save Better to say it saves cutting and pasting, which is a damn good thing -- even if macros are an old fashioned way of doing it. The biggest benefit of macros isn't saving the

Re: help in developing soft and hardlockup detection tool

2013-12-16 Thread Valdis . Kletnieks
On Mon, 16 Dec 2013 09:25:21 +0800, Peter Teoh said: the interrupt is disabled. but u can of course do some pre-calculation: for your CPU, for platform, do a precise low level accurate timing of CPU to assess how many instructions of a certain types is need to achieve a duration, say 1

Re: How to test my patches for the (staging) android driver?

2013-12-04 Thread Valdis . Kletnieks
On Wed, 04 Dec 2013 16:08:52 +0100, Matthias Beyer said: How to test my code beside compiling it? Do I even have a possibility to test it or should I just send it to you? If at all possible, you should cross-compile for an appropriate architecture and actually boot and test the code in

Re: watchdog pet in kernel module

2013-12-04 Thread Valdis . Kletnieks
On Wed, 04 Dec 2013 16:45:44 -0800, Vipul Jain said: If you don't mind can you please provide me more insight as what can be false alarm I can encounter to move pet inside kernel module? The issue isn't false alarms - it's failure to alarm when it should. The problem is that it's possible for

Re: How can I 'getchar()' in module code?

2013-12-03 Thread Valdis . Kletnieks
On Tue, 03 Dec 2013 20:35:41 +0800, 乃宏周 said: For debugging purpose, I want something like 'getchar()' that can pause execution in the module code. Do any candidates I can choose? The problem is that pausing execution in module code is dangerous, as if you hold any locks or anything like

Re: watchdog pet in kernel module

2013-12-03 Thread Valdis . Kletnieks
On Tue, 03 Dec 2013 13:15:32 -0800, Vipul Jain said: currently we configure/pet the watchdog from user space via /dev/ipmi0 device interface and I would like to do the pet part from kernel module. That's actually defeating the purpose. If you do it from the kernel, you keep the watchdog from

Re: Updating the kernel

2013-11-22 Thread Valdis . Kletnieks
On Fri, 22 Nov 2013 12:21:59 +0400, Vasiliy Tolstov said: After some time i need to update kernel. How can i deal with it with minimal downtime not using ksplice? Kexec? The usual stock answer is run two instances with some sort of High-Availability package between the two of them. Fail over

Re: Updating the kernel

2013-11-20 Thread Valdis . Kletnieks
On Tue, 19 Nov 2013 15:39:06 -0500, Soham Chakraborty said: Vladis, I hear ya and agree to that. Problem is I have seen big and by big, I mean big infrastructures asking for ksplice since certain sales people of certain company introduced them to the utopia that is called

Re: Updating the kernel

2013-11-19 Thread Valdis . Kletnieks
On Tue, 19 Nov 2013 09:48:27 -0500, Soham Chakraborty said: I don't really think ksplice has garnered much love from upstream. The most common word used upstream to describe ksplice is bletcherous. The reason it's disliked is because it's a poor solution for the problem. Although ksplice-like

Re: Linux Kernel - Modifying a module_param variable from other drivers

2013-11-14 Thread Valdis . Kletnieks
On Thu, 14 Nov 2013 18:32:05 +0900, manty kuma said: I see that when we declare a variable as module_param from a driver, i can see it listed in /sys/module/xxx/parameters/ Ex : /sys/module/usbcore/parameters/autosuspend we can modify and read it with echo and cat commands from

Re: Linux Kernel - Modifying a module_param variable from other drivers

2013-11-14 Thread Valdis . Kletnieks
On Fri, 15 Nov 2013 10:33:40 +0900, manty kuma said: I am not talking about all the variables. i am talking about variables which are declared as module_param. These variables can anyways be changed from shell prompt using echo and cat like i mentioned in the desciption. If you actually chase

Re: How to find out which part of code is changing a particular data structure.

2013-11-08 Thread Valdis . Kletnieks
On Thu, 07 Nov 2013 23:23:18 -0800, kiran kumar said: Can you define that location as read only(i.e constant)?. This is only for debug prupose, later you can remove. Note that this requires 2 things: 1) A kernel built with CONFIG_DEBUG_RODATA=y 2) The structure needs to have a compile-time

Re: GIt Checkout of Kernel Repo

2013-11-06 Thread Valdis . Kletnieks
On Thu, 07 Nov 2013 00:31:06 +0530, Arun M Kumar said: git tag -l | less would list out all the tags associated with a build including the release candidates... But I am getting tags ONLY till v3.9.9 Double-check. The tags are lexically sorted, not numerically. You'll probably find v3.10

Re: own distribution Centos 6.4

2013-11-05 Thread Valdis . Kletnieks
On Tue, 05 Nov 2013 10:35:26 +0530, PV Juliet said: Kernel Panic - not syncing: Attempted to kill init! Pid: 1 comm: init Not tainted. I have put all the dependencies also . This usually means you've botched the initrd/initramfs. pgpL7IUO0NusI.pgp Description: PGP signature

Re: How to prevent other processes from being scheduled

2013-11-05 Thread Valdis . Kletnieks
On Wed, 06 Nov 2013 00:51:03 +0900, J.Hwan Kim said: How can I prevent other processes than my specific application from being scheduled? What problem are you trying to solve by not allowing other processes to run? There's almost certainly a better approach. pgp63G3Ofeoja.pgp Description:

Re: Writing to user file from kernel

2013-11-05 Thread Valdis . Kletnieks
On Tue, 05 Nov 2013 16:03:57 -0700, neha naik said: 'vfs_read' is strightforward but i don't understand the api 'splice_direct_to_actor'. Is there any documentation which will explain it to me and where it is used. Because as i see it you can read a file using either of the two 'vfs_read'

Re: PF_RING on Mellanox Card

2013-11-03 Thread Valdis . Kletnieks
On Sat, 02 Nov 2013 00:48:04 -0700, Robert Clove said: I want to know has anyone used the PF_RING on the Mellanox NIC card? You do realize that Mellanox has literally *dozens* of models of NIC cards, right? What card exactly? pgpWATMI6Spdb.pgp Description: PGP signature

Re: need advice on howto access memory from fpga and cpu

2013-10-30 Thread Valdis . Kletnieks
On Wed, 30 Oct 2013 17:17:44 +0100, Kai said: One more question: Currently I'm using the book Linux Device Drivers 3rd Edition (2005) as a reference, and it's discussing Kernel 2.6.10. Do you think that's still okay, or should I get/buy a more recent book on this topic, and which would you

Re: What the following command states

2013-10-29 Thread Valdis . Kletnieks
On Tue, 29 Oct 2013 18:04:38 +0530, Robert Clove said: cat /proc/sys/net/ipv4/tcp_mem when i run the above command i get the following output 6182880 8243840 12365760 What these value states? from Documentation/networking/ip-sysctl.txt tcp_mem - vector of 3 INTEGERs: min, pressure, max

Re: Module that enforces etc/limits.conf

2013-10-22 Thread Valdis . Kletnieks
On Tue, 22 Oct 2013 17:16:27 +0530, Paul Davies C said: May I know which kernel module / code part that enforce the limits specified in /etc/limits.conf file? There's no one part that does it. It's done inline for each limit, at the point in the code that needs the check. What are you trying

Re: adding a system call in Linux kernel v3.11

2013-10-20 Thread Valdis . Kletnieks
On Fri, 18 Oct 2013 23:31:54 -0700, David said: fedora live desktop x86_64-19-1. I followed the code posted on http://lists.kernelnewbies.org/pipermail/kernelnewbies/2013-July/008598.html but I get a warning when I go to make modules. It is: CALLscripts/checksyscalls.sh stdin:1226:2:

Re: v3.12-rc4 does not find my WLAN chip - how to submit to lkml/appropriate subml?

2013-10-12 Thread Valdis . Kletnieks
On Sat, 12 Oct 2013 16:01:21 +0200, Matthias Beyer said: I just compiled v3.12-rc4 on my other device and rebooted it. It does not find my WLAN-Chip! The log (at /var/log/kern.log) says ath5k phy0: Atheros AR2425 chip found (MAC: 0xe2, PHY: 0x70) for the _old_ kernel (3.2.0-4-amd64).

Re: file system sector size?

2013-10-09 Thread Valdis . Kletnieks
On Tue, 08 Oct 2013 13:25:29 -0700, Guangyu Sun said: As far as I know sector size comes with the storage device and cannot be changed, while block size is set by file system. On some high-end RAID-based storage devices, the effective sector size is basically the raid stripe size and

Re: [PATCH 1/3] Minimum wrapfs rename

2013-10-03 Thread Valdis . Kletnieks
On Wed, 02 Oct 2013 15:47:33 +0100, Alin Dobre said: +++ b/fs/idmapfs/Kconfig @@ -0,0 +1,8 @@ +config IDMAP_FS + tristate Idmapfs stackable file system (EXPERIMENTAL) + help + Wrapfs is a stackable file system which simply passes its + operations to the lower layer.

Re: working of migrate_page (exported) function in mm/migrate.c linux Kernel

2013-09-22 Thread Valdis . Kletnieks
On Mon, 23 Sep 2013 09:00:21 +0800, ajay saini said: Is it used somewhere ? [~] cd /usr/src/linux-next/ [/usr/src/linux-next] find [a-z]* -name '*.[ch]' | xargs grep migrate_page | grep -v migrate_pages And start searching from there. You'll probably have to iterate several times, because

Re: How to create sysfs file and associate it with file operations like mmap

2013-09-18 Thread Valdis . Kletnieks
On Wed, 18 Sep 2013 15:49:56 +0530, Niroj Pokhrel said: I want to create a sysfs file and associate it with several file opeations like open,close and mmap. Actually, probably not. There's some rules (like one value per file) that sysfs should follow, which makes it a poor fit for mmap.

Re: Formatting timestamps in the kernel

2013-09-17 Thread Valdis . Kletnieks
On Tue, 17 Sep 2013 16:18:51 -0700, Neil Baylis said: I think I read somewhere that timezones are considered a userspace concept, and as such are not supported within the kernel. Correct. Your best bet is probably to use seconds and fractions since boot, since you can steal all the code you

Re: Plug/unplug events of headphone

2013-09-14 Thread Valdis . Kletnieks
On Sun, 15 Sep 2013 01:12:30 +1100, Dmitry Kolesov said: I want to catch plug/unplug events of headphone. Could anybody explain where I need to search? If you explained a bit more what you're trying to do, we'd be able to give better advice. Are you trying to catch them from userspace, or

Re: Plug/unplug events of headphone

2013-09-14 Thread Valdis . Kletnieks
On Sun, 15 Sep 2013 02:13:11 +1100, you said: I can not listen sound from speakers after reboot laptop if I power off laptop with headphone. And I need to plug/unplug headphone to listen music from speakers. That sounds like a bug with the ALSA drivers not correctly sensing the state of the

Re: WEP/WPA/WPA2 implementation in software

2013-09-13 Thread Valdis . Kletnieks
On Fri, 13 Sep 2013 17:23:22 +0530, Prabhunath G said: Suppose there is no hardware support for encryption/decryption for Wi-Fi devices 1) Do not use WEP. It's busted. It's *known* busted. You transmit packets for more than a minute or so using WEP, you may as well not bother with

Re: inode of anonymity file

2013-09-12 Thread Valdis . Kletnieks
On Thu, 12 Sep 2013 05:08:24 -, binoy.ja...@wipro.com said: Are you talking about an orphaned inode? No - orphaned is the state the inode ends up in if the file was open but unlinked when the system is rebooted. At that point, the inode is still there (since it was never reclaimed before

Re: inode of anonymity file

2013-09-11 Thread Valdis . Kletnieks
On Wed, 11 Sep 2013 18:30:31 +0800, Grissiom said: I found that `anon_inode_getfd` and `anon_inode_getfile` could create anonymity files that I could implement my own read/write etc without both writing drivers nor expose the structure into the file system. I suspect that your understanding of

Re: stop build of kernel when there is a compilation error when using make -j

2013-09-11 Thread Valdis . Kletnieks
On Wed, 11 Sep 2013 14:14:05 -, binoy.ja...@wipro.com said: Did you try make -S Actually, that's the default, and -S only exists so you can cancel an inherited -k from above. The problem is that if 'make -j4' launches 4 sub-makes, the one that hits the error of course stops right away,

Re: inode of anonymity file

2013-09-11 Thread Valdis . Kletnieks
On Thu, 12 Sep 2013 11:38:18 +0800, Grissiom said: One question about the unlinked file: if I write a lot of data into a unlinked file, where will the data be? On the disk or in the RAM? If the data will be on the disk, where is it? Maybe on disk, maybe in RAM, same as any other file data.

Re: Introducing Myself, Looking to Learn

2013-09-04 Thread Valdis . Kletnieks
On Wed, 04 Sep 2013 00:59:03 +0530, Varad Gautam said: I have also subscribed to the LKML, but find it completely incomprehensible! As a beginner, would it be better to work with the kernel of a specific OS (I'm running Ubuntu), or work on the upstream kernel? Depends what you're trying to

Re: Introducing Myself, Looking to Learn

2013-09-03 Thread Valdis . Kletnieks
On Wed, 04 Sep 2013 02:05:42 +0530, Varad Gautam said: Hi Vladis! Thanks for replying. I think I would be fine with writing real code once I figure out what goes where. Well, assuming you have a background as a professional or very serious amateur programmer, *and* you have a *particular* drive

Re: Dcache_lock replacement

2013-09-02 Thread Valdis . Kletnieks
Since lot of things have changed from 2.6.18 to 3.8 and I have taken a lot of care to replace the old kernel APIs with the newer ones but then too there have been certain things I haven't been able to replace and dcache_lock is one of them. Due to the absence of dcache_lock, I have not been

Re: Need help for getting started

2013-09-02 Thread Valdis . Kletnieks
On Mon, 02 Sep 2013 17:29:19 +0700, 901...@gmail.com said: Hello all, I am a newbie here. I'd like to contribute in architectures, kernel features, virtualization, and drivers parts, but I don't know where is a good way to start. I have looked for some advice but I have had a hard time to

Re: [dm-devel] [RFC] dm-lc: plan to go to staging

2013-08-30 Thread Valdis . Kletnieks
On Fri, 30 Aug 2013 21:33:29 +0900, Akira Hayakawa said: Candidates: 1) logcache Not too long but explaining enough but looks little bit dull to me. Descriptive but dull naming is a much underrated quality in software packages. Consider the package HarfBuzz. As my daughter put it, Sounds

Re: Given a page, How to get the NUMA node id of this page

2013-08-29 Thread Valdis . Kletnieks
On Fri, 30 Aug 2013 02:43:00 +0800, ajay saini said: I am working on a checkpoint/Restart Linux kernel module. Have you looked at the already existing checkpoint/restart support? (and C/R is a lot harder to get right than you think - turns out you need all sorts of infrastructure. The various

Re: Given a page, How to get the NUMA node id of this page

2013-08-29 Thread Valdis . Kletnieks
On Fri, 30 Aug 2013 04:39:14 +0800, ajay saini said: I am working on BLCR (a checkpoint/Restart Linux kernel module), currently it does not have this information. Yes, but why are you re-inventing the wheel? Is there a reason the existing in-kernel support for C/R isn't usable for your

Re: First userspace executalbe run at boot up

2013-08-27 Thread Valdis . Kletnieks
On Tue, 27 Aug 2013 11:00:00 +0200, Matthias Brugger said: All of them try to execute init by invoking run_init_process. So my question is, why does the rdinit= parameter exist, I suppose for reasons of compatibility with older kernel versions. But why it is set to /init? Consider the case

Re: Using same .config on different machines

2013-08-27 Thread Valdis . Kletnieks
On Tue, 27 Aug 2013 16:15:20 +0530, Arun M Kumar said: Is it OK to use same .config file on different machines. As long as the .config includes all the moduled needed for all the machines in question. That's basically what a distro kernel does - include all the drivers for all supported

Re: /dev/sda to ata_host

2013-08-20 Thread Valdis . Kletnieks
On Tue, 20 Aug 2013 00:25:24 -0700, Com Developer said: I am doing some custom work and I am not interested in recompiling kernel with ahci and libata compiled separately. That still doesn't actually explain what problem you're trying to solve by finding the ata_host structure. I suspect it's

Re: /proc/net/dev no such file or dir

2013-08-13 Thread Valdis . Kletnieks
On Tue, 13 Aug 2013 21:43:55 +0800, Hatte John said: I have not ever mount /sys and /proc filesystems, so is there other way to chech the host's ip address and netdevice information? If in fact /sys and /proc aren't getting mounted, a *whole lot* of stuff won't work (for instance, /bin/ps

Re: A question about -mm tree and -next tree.

2013-08-06 Thread Valdis . Kletnieks
On Tue, 06 Aug 2013 21:27:27 +0800, Zhan Jianyu said: I found that most of the -mm patches are in -next, which means they will be tested more by all developers , but there are still some patches are not included in -next tree. So why are they special and how they make

Re: Network Driver From Scrach

2013-08-06 Thread Valdis . Kletnieks
On Tue, 06 Aug 2013 10:22:23 -0700, Robert Clove said: I want to first understand and then write a network driver for simple Ethernet device (actually instead of inbuilt network driver i want to run my network driver). simple Ethernet device. That's the first bug you need to fix in your

Re: Where to call my init() from (without LKM)?

2013-08-04 Thread Valdis . Kletnieks
On Sun, 04 Aug 2013 10:40:42 +0100, George White said: Most of my code is implemented in a new file I created  under /kernel/ myfile.c and added in the main Makefile (other parts of the code are spread around the existing code as edits). Question A:  Is that a good idea? Alternatives?

Re: Reduce boot time console messages?

2013-08-04 Thread Valdis . Kletnieks
On Mon, 05 Aug 2013 11:07:26 +0800, Woody Wu said: Valdis, thank you very much. I just passed loglevel=7 as kernel command line and hope it can suspress KERN_DEBUG messages printed out to console at boot time. But, it seems not work. A lot of debug level messages from jffs2 module still

Re: Reduce boot time console messages?

2013-08-03 Thread Valdis . Kletnieks
On Sat, 03 Aug 2013 20:27:55 +0800, Woody Wu said: Hi, My kernel is printing too many messages at boot time from a special device driver (j2ffs filesystem). I belive these kernel messages are level DEBUG. If don't change the kernel code, is there anyway to print only some higher level of

Re: Conceptual questions about device driver

2013-08-02 Thread Valdis . Kletnieks
On Thu, 01 Aug 2013 23:21:48 -0400, Greg Freemyer said: I should know, but I don't think your question makes sense. Data transfers are axles immediately upon receipt by the drive. When the drive actually puts it to stable storage there is not another ack message. I believe disk drives can

Re: Application Debugging

2013-08-02 Thread Valdis . Kletnieks
On Fri, 02 Aug 2013 10:05:04 -0700, Robert Clove said: Like when the gui is opened which function is executed and when i press some button on gui which function is executed. If yes please tell how,i am all new to linux . gdb, strace, ctags, and cscope are your friends. pgpET9r13MURc.pgp

Re: Managing linux-next tree

2013-08-01 Thread Valdis . Kletnieks
On Thu, 01 Aug 2013 15:33:21 +0530, Kumar Amit Mehta said: 1. Clone the tree (once): $ git clone git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git This won't do what you want. What you want is something more like: $ git clone

Re: Career in Linux Internals and Embedded Systems

2013-08-01 Thread Valdis . Kletnieks
On Thu, 01 Aug 2013 19:29:52 +0530, Satya Prakash Prasad said: If I want to pursue my career in Linux Internals / Embedded systems what things should I learn or be expertise in? I have plans to buy Raspberry PI. But I don't know what projects to practice or rather what programs to write to

Re: Getting Started

2013-07-31 Thread Valdis . Kletnieks
On Wed, 31 Jul 2013 10:32:59 +0530, you said: I am a computer science student. I want to contribute to the open source projects, debugging. As it is my first time, i need some guidance. (a) You're better off replying to the list, as you then get answers from others besides me. Redirecting

Re: Getting Started

2013-07-30 Thread Valdis . Kletnieks
On Tue, 30 Jul 2013 23:03:24 +0530, Karan Dev said: hey, I am new here. I'd like to contribute to your organisation. Could someone guide me along ? We could give you more guidance if we understood *why* you want to contribute. Different people help for different reasons - the advice we give

Re: Which repo should I clone?

2013-07-29 Thread Valdis . Kletnieks
On Mon, 29 Jul 2013 10:25:53 +0300, Alexandru Juncu said: For a little more unstable version, there's the linux-next repo (I think the address is this [4]). For some definition of little more unstable'. :) V3.10 is out, and Linus just tagged v3.11-rc3 a few hours ago, which means that 3.11

Re: Direct IO and Page cache

2013-07-26 Thread Valdis . Kletnieks
On Thu, 25 Jul 2013 23:15:49 -0400, Kumar amit mehta said: applications are being written. So one bad day somebody comes up with an application which does both these two types of IO(one that goes through page cache and the other that doesn't) and in that application, one instance is writing

Re: Direct IO and Page cache

2013-07-26 Thread Valdis . Kletnieks
On Fri, 26 Jul 2013 00:02:31 -0400, Kumar amit mehta said: So leaving the hardware at the mercy of the application doesn't sound like a good practice. This __may__ compromise kernel stability too. Also think of this: In what possible way does it compromise kernel stability?: In app1: fdx =

Re: mmap how does kernel know a page is mmaped

2013-07-25 Thread Valdis . Kletnieks
On Thu, 25 Jul 2013 09:14:03 -0700, kernel neophyte said: Could anyone please explain, how mmap works underneath ? when kernel traveses pgd-pud-pmd-pte how does it know that a particular page is a mmaped page ? is there any special flag ? Why would the address mapping hardware even *care*

Re: mmap how does kernel know a page is mmaped

2013-07-25 Thread Valdis . Kletnieks
On Thu, 25 Jul 2013 10:52:43 -0700, kernel neophyte said: I am sorry maybe I did not ask the question correctly, all I want to know is how mmap works underneath, given an address X how does kernel figure out its a mmaped page ? You missed the point. The kernel never checks if it's an mmap'ed

Re: Debugging a Stall or a Freeze

2013-07-25 Thread Valdis . Kletnieks
On Thu, 25 Jul 2013 13:56:47 -0400, Salam Farhat said: When the guest OS freezes I get the following messages seen below. I would like to know what is a good approach for debugging this issue. I am not sure what a process stall is. Is that a deadlock? [ 780.357876] BUG: soft lockup - CPU#0

Re: Need help to understand system calls

2013-07-25 Thread Valdis . Kletnieks
On Fri, 26 Jul 2013 00:09:21 +0530, Nitisha Jain said: But what is this perf output showing me then ? Are generic_file_buffered_write , ext4_file_write etc all system calls ? No, they're C functions inside the kernel. pgp4w1s0jTS57.pgp Description: PGP signature

Re: mmap how does kernel know a page is mmaped

2013-07-25 Thread Valdis . Kletnieks
On Thu, 25 Jul 2013 14:33:21 -0400, Greg Freemyer said: There are 3 situations I can think of offhand, but I don't know which one you are interested in: 1) Userspace does a read/write to a data page that is not memory resident and the page is backed by a mmap'ed file. 2) Userspace does a

Re: mmap how does kernel know a page is mmaped

2013-07-25 Thread Valdis . Kletnieks
On Thu, 25 Jul 2013 16:57:44 -0700, kernel neophyte said: I am sorry, its still not clear to me. All I am asking is I want to know and understand how mmap works, given an address *X*, how does the Linux kernel figure out that *X* is an mmaped page? Before you ask *how* it does it, first

Re: preemptive kernels and the use of smp_processor_id()

2013-07-23 Thread Valdis . Kletnieks
On Tue, 09 Jul 2013 12:20:41 +0200, Christian Parpart said: So it seems the kernel module I am porting assumed to always run on the same CPU core once entered kernelspace, but on a preemptive system you cannot guarantee that. Correct. You probably want to fix the assumption(s) in the kernel

Re: Where is the system call table in linux kernel v3.9?

2013-07-19 Thread Valdis . Kletnieks
On Fri, 19 Jul 2013 13:25:35 +0530, Prashant Shah said: You can even use filp_open(), vfs_read(), vfs_write() if sys_* is not available https://github.com/prashants/km/blob/master/filerw/filerw.c The reasons to not do file I/O from inside the kernel are many and well documented. Of course,

Re: implicit declaration of some function error

2013-07-19 Thread Valdis . Kletnieks
On Fri, 19 Jul 2013 16:49:13 +0530, Srinivas Ganji said: This is ONLY a hint for finding the header files in the /usr/src/linux directory. I do generally like this. find include -type f | xargs grep kthread_run Remember that there's arch-dependent headers as well. You may want this: find

Re: Where is the system call table in linux kernel v3.9?

2013-07-18 Thread Valdis . Kletnieks
On Thu, 18 Jul 2013 18:14:22 +0530, Sudip Mukherjee said: Hi In 3.10.1 the system call table is in arch/x86/syscalls/syscall_32.tbl Only for x86. You're on an ARM or PowerPC or MIPS or any of the other 27 or so architectures we support, it's elsewhere. ;) pgp7413KqpI0x.pgp Description: PGP

Re: Is the Kernel Janitors project still alive?

2013-07-18 Thread Valdis . Kletnieks
On Thu, 18 Jul 2013 08:33:05 -0500, Christopher Stanton said: Is there some live version of this project somewhere or has there been a replacement? A unified list of needed but non-critical clean-ups? Or, is it suggested people just look at bug reports? Janitors is pretty much deceased, for

Re: Kernel Testing (was Re: Is the Kernel Janitors project still alive?)

2013-07-18 Thread Valdis . Kletnieks
On Thu, 18 Jul 2013 10:58:36 -0700, Arlie Stephens said: Does the linux kernel have any kind of regression test package? If so, where can I find it? If not, does anyone know of ongoing attempts to create one? A quick web search gave me a few pointers to attempts at this: The Google-foo is

Re: [PATCH] zram percpu implementation

2013-07-16 Thread Valdis . Kletnieks
On Wed, 17 Jul 2013 00:27:34 +0530, mani said: This patch will create a percpu structures compression algo. 1. Takes extra memory for workspace buffers. I haven't seen any performance gain with this need to find the root cause. My first guess is that the higher-level zram stuff is submitting

Re: Inline Macro issue

2013-07-15 Thread Valdis . Kletnieks
On Mon, 15 Jul 2013 17:39:15 +0530, Mandeep Sandhu said: #define push_root() \ recursive_mutex_lock(context-id_lock);\ context-uid = current-fsuid; \ context-gid = current-fsgid; \ do {

Re: Rebuild a changed kernel quickly with make?

2013-07-09 Thread Valdis . Kletnieks
On Tue, 09 Jul 2013 13:16:53 +0530, Srinivas Ganji said: You can pass the name of the target to the make for building only the specified files and objects. Suppose, if I changed some modifications in storage files, then I need to do make as shown below, from the top level directory i.e.

Re: Debugging techniques inside kernel

2013-07-08 Thread Valdis . Kletnieks
On Mon, 08 Jul 2013 08:18:02 -0700, Anand Arumugam said: Try using strace and see if all of the different crashes have the same or similar looking call stack. strace is userspace, and *highly* unlikely to track down random memory corruption inside the kernel. Random kernel corruption usually

Re: Question about NETDEV_REGISTER and NETDEV_UNREGISTER events

2013-07-03 Thread Valdis . Kletnieks
On Wed, 03 Jul 2013 16:15:02 +0300, Kevin Wilson said: Hello, I am having a machine with two ethernet devices. Is there a way to generate NETDEV_REGISTER or NETDEV_UNREGISTER events, besides rmmod/insmod of the device driver ? What use case do you have for generating those at other times?

Re: Kernel Linux updating

2013-06-29 Thread Valdis . Kletnieks
On Fri, 28 Jun 2013 11:23:57 +0200, Mylene Josserand said: And we encountered some problems (about CAN controller to be precise). In the CAN mailist, Luka Rahne has the same problem has ours with the 3.0.3 kernel. He tested the 3.0.81 and the problem seems to be gone. So, also, I wanted to

Re: printk and kernel log

2013-06-27 Thread Valdis . Kletnieks
On Thu, 27 Jun 2013 18:08:09 +0300, Kevin Wilson said: Jun 24 03:43:06 localhost kernel: [ 1858.148661] in my_func1 where is the localhost from ? That's added by your syslog daemon (whatever that might be). It's basically the value returned by /bin/hostname machines on which the hostname

Re: printk and kernel log

2013-06-27 Thread Valdis . Kletnieks
On Thu, 27 Jun 2013 18:46:50 +0300, Kevin Wilson said: Thanks, but unfortuantely this is not so. On this machine I have: /bin/hostname amd1 Weird. Maybe you have a flaky syslog() call that writes UDP packets to the local host, rather than using the unix-domain socket at /dev/log - when the

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