error : insmod
hi all, while inserting module to the linux kernel, m facing this problem ---ERROR- sunil@ubuntu:~/test/drive$ insmod helloworld.ko insmod: error inserting 'helloworld.ko': -1 Operation not permitted sunil@ubuntu:~/test/drive$ sudo modprobe helloworld FATAL: Module helloworld not found. please help!! thanks regards Sunil ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
RE: error : insmod
Try it through root access. Regards ASHU -Original Message- From: kernelnewbies-boun...@kernelnewbies.org [mailto:kernelnewbies-boun...@kernelnewbies.org] On Behalf Of sunil Sent: Monday, February 11, 2013 3:24 PM To: kernelnewbies@kernelnewbies.org Subject: error : insmod hi all, while inserting module to the linux kernel, m facing this problem ---ERROR- sunil@ubuntu:~/test/drive$ insmod helloworld.ko insmod: error inserting 'helloworld.ko': -1 Operation not permitted sunil@ubuntu:~/test/drive$ sudo modprobe helloworld FATAL: Module helloworld not found. please help!! thanks regards Sunil ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: error : insmod
On 02/11/2013 01:54 AM, sunil wrote: hi all, while inserting module to the linux kernel, m facing this problem ---ERROR- sunil@ubuntu:~/test/drive$ insmod helloworld.ko insmod: error inserting 'helloworld.ko': -1 Operation not permitted sunil@ubuntu:~/test/drive$ sudo modprobe helloworld FATAL: Module helloworld not found. It is a path issue, you need to specify the entire path to helloworld.ko. For example: sudo insmod /path/to/your/helloworld.ko signature.asc Description: OpenPGP digital signature ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: error : insmod
On 2013-02-11 15:24:08 (+0530), sunil sunil.slvp...@gmail.com wrote: while inserting module to the linux kernel, m facing this problem ---ERROR- sunil@ubuntu:~/test/drive$ insmod helloworld.ko insmod: error inserting 'helloworld.ko': -1 Operation not permitted For obvious reasons normal users are not allowed to load kernel modules. This requires root access (or more accurately, CAP_SYS_MODULE capabilities). That's why your insmod fails. sunil@ubuntu:~/test/drive$ sudo modprobe helloworld FATAL: Module helloworld not found. This is a different action from 'insmod helloworld.ko'. modprobe tries to load the module from /lib/modules/`uname -r`. It's slightly more convenient because it will also load all modules this one depends on. In this case this fails because your module doesn't actually live in /lib/modules/ Try sudo insmod helloworld.ko instead. Regards, Kristof ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: error : insmod
On 2013-02-11 16:10:38 (+0530), sunil sunil.slvp...@gmail.com wrote: -output sunil@ubuntu:~/test/drive$ sudo insmod ./helloworld.ko insmod: error inserting './helloworld.ko': -1 File exists This means you've already loaded the module. Try 'sudo rmmod helloworld' to unload it first. This should generate the 'Goodbye, cruel world' dmesg trace. After that you can load the module again. Regards, Kristof ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: error : insmod
Hi kristof, when i executed the below line. i din't get what i suppose to get...the message hello, world.. did i miss any steps sunil@ubuntu:~/test/drive$ sudo insmod helloworld.ko On Mon, Feb 11, 2013 at 4:34 PM, Kristof Provost kris...@sigsegv.be wrote: On 2013-02-11 16:24:17 (+0530), sunil sunil.slvp...@gmail.com wrote: Have a look at this: donno wats happening: sunil@ubuntu:~/test/drive$ sudo rmmod helloworld sunil@ubuntu:~/test/drive$ lsmod|grep hellow* Binary file helloworld.ko matches Binary file helloworld.o matches This doesn't actually do what you seem to think it does. You're not passing the 'hellow*' argument to grep. The 'hellow*' is first expaned by your shell, so it probably turns that command line into 'lsmod | grep helloworld.c helloworld.o helloworld.ko'. Try using 'lsmod | grep hellow' instead (i.e. without the *). sunil@ubuntu:~/test/drive$ modprobe -r helloworld FATAL: Module helloworld not found. Obviously, because your previous command succeeded. The module is no longer loaded. Regards, Kristof PS: Please don't top-post. PS 2: Please keep the mailing list in cc. -- Regards, Sunil A S ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Use of copy_to_user() and copy_from_user() functions
Hi All, To read/write data to user-space from kernel-space we use copy_from_user() and copy_to_user() functions. What is the use of these function? Why kernel can't directly access user address and read/write on to it? Can any one explain why kernel can't directly access the user-space address. Thanks ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: error : insmod
On 2013-02-11 16:50:45 (+0530), sunil sunil.slvp...@gmail.com wrote: when i executed the below line. i din't get what i suppose to get...the message hello, world.. did i miss any steps sunil@ubuntu:~/test/drive$ sudo insmod helloworld.ko The traces you've inserted in your kernel module do not print to stdout. They get logged in the kernel ring buffer. Try 'dmesg' after loading your module. Regards, Kristof ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Use of copy_to_user() and copy_from_user() functions
On Mon, Feb 11, 2013 at 4:51 PM, पारस bepa...@gmail.com wrote: Hi All, To read/write data to user-space from kernel-space we use copy_from_user() and copy_to_user() functions. What is the use of these function? Why kernel can't directly access user address and read/write on to it? Can any one explain why kernel can't directly access the user-space address. There are a lot resources out there which answer this question adequately in detail (just google for them). I'll give a short answer here: 'User-space' is essentially a particular process' address space, i.e the pages (of physical memory) that have been mapped to this process' virtual memory. Since pages of virtual memory _might_ be swapped out by the kernel, one cannot directly transfer data from the kernel memory to the user mapped memory. For this reason, copy_to/from_user() family of functions is there, which verify first that the user space address (pointed to by the user-space pointer) is valid and accessible and _then_ transfer data to/from it. If the page corresponding to the address pointed to by the user-space pointer has been swapped out, the kernel will first swap in that page and then do the transfer. CMIIW. HTH, -mandeep Thanks ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Kernel code interrupted by Timer
Well, my bad. I was wrong there. Your example was correct. Even in a multi-kernel like Barrelfish, each core manages only its own share of memory. RAM is explicitly partitioned between cores running on each kernel and any data structures that need to be shared across cores have to be replicated in each of the memory partitions and consistency maintained through IPC. ~Gaurav On Fri, Feb 8, 2013 at 10:29 PM, Gaurav Jain gjainroor...@gmail.com wrote: I guess you misinterpreted me... A multi-kernel like Barrelfish would have separate kernel images running on different cores, but each of the core/kernel would be able to address the *entire* physical memory (including any memory-mapped devices). Hence, the database would still be addressable/reachable from all cores. Traditional locking mechanisms to protect the database (like in a single-kernel Linux) would be good here, too. OR, like in Barrelfish, we could have explicit inter-core communication messages to implement synchronization/consistency. ~ Gaurav On Fri, Feb 8, 2013 at 9:34 PM, Jeff Haran jeff.ha...@citrix.com wrote: Well, for instance what we do. We maintain a big database of cell phone user IP addresses and other info in a kernel module running on a 24 core X86-64 system. All 24 cores can and do access that data. If each core had access to only a single partition of memory, then that DB would have to be spread across the various partitions and if the one core that could access a specific cell phone user’s info was busy while others were idle, access to that user’s would be delayed. The application is quite performance sensitive so having the ability for all cores to operate on all data makes for better performance. ** ** Jeff ** ** *From:* Gaurav Jain [mailto:gjainroor...@gmail.com] *Sent:* Friday, February 08, 2013 11:54 AM *To:* Jeff Haran *Subject:* Re: Kernel code interrupted by Timer ** ** you can solve problems that can’t be easily solved if all the data is partitioned by CPU core. ** ** Can you please give an example or two of the aforementioned problems? I can think of efficient scheduling - a single kernel knowing what cores/processors are idle would help make better decisions without the overhead of message passing in separate kernels on separate cores. ** ** ~Gaurav ** ** On Fri, Feb 8, 2013 at 8:16 PM, Jeff Haran jeff.ha...@citrix.com wrote: I did not write Linux, so just guessing here. I don’t think the issue is so much kernel images as shared access to kernel data. The synchronization primitives in the kernel (spin locks, read-write locks, RCU, etc) are there to protect data from being corrupted during concurrent access, not code. I am not familiar with barrelfish but I think most modern OSes, for instance the various BSD derivatives, work like this. I have no recent experience with it, but I’d bet Windows does the same thing. If you can run multiple cores on the same data safely by providing proper locking, you can solve problems that can’t be easily solved if all the data is partitioned by CPU core. Getting the locking right though can be a challenge, which is of course good for software engineer job security. 8^) Jeff *From:* Gaurav Jain [mailto:gjainroor...@gmail.com] *Sent:* Friday, February 08, 2013 11:03 AM *To:* Jeff Haran *Subject:* Re: Kernel code interrupted by Timer On multi-core systems this should be done regardless of whether kernel pre-emption is enabled or not -- Do you know why such a design decision was made - That a single kernel image should manage all the cores! I have worked on Barrelfish ( http://www.barrelfish.org/) a bit, and it boots a separate kernel on each of the cores. To me that appears to be the more intuitive approach. What advantages do we get by having a single kernel image on all cores? Is the convenience of being in the same address space (the single kernel's) at all cores at all times, the only/major reason? ~Gaurav On Fri, Feb 8, 2013 at 7:51 PM, Jeff Haran jeff.ha...@citrix.com wrote: I think you will find that this is a matter of kernel configuration. If kernel pre-emption is enabled at build time, then following the interrupt another process could get scheduled and it wouldn’t matter what interrupt went off. Typically some sort of explicit locking or RCU is used to protect critical sections in cases like this. On multi-core systems this should be done regardless of whether kernel pre-emption is enabled or not. Jeff Haran *From:* kernelnewbies-boun...@kernelnewbies.org [mailto: kernelnewbies-boun...@kernelnewbies.org] *On Behalf Of *Gaurav Jain *Sent:* Friday, February 08, 2013 9:09 AM *To:* Kernel Newbies *Subject:* Kernel code interrupted by Timer What happens if the kernel executing in some process context (let's say executing
[PATCH] bind micmute led to capslock led on thinkpads
Hi folks, The attached patch binds the capslock light to the micmute light on my Thinkpad. It works really well. But it's definitely the wrong way to be doing things. There are two problems I'd like to solve a better way: 1) How do I find a pointer to the led_device struct for that led, so that I can call brightness_set on it? 2) How do I hook the kbd_set_leds functions without having to patch atkbd.c? I'm more interested in (1) than (2), but insights on either would be welcome. Thanks! Jason thinkpad-bind-micmute-led-to-capslock-led.patch Description: Binary data ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: MAX limit of file descriptor
On Mon, Feb 11, 2013 at 5:07 AM, horseriver horseriv...@gmail.com wrote: thanks! Actually , my question comes from network performance ,I want to know ,in per second ,the maximum of tcp connections that can be dealed with by my server. AFAIK, the only way to find out is by doing benchmark by your own. You can use tools like netperf for that purpose. -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: MAX limit of file descriptor
On Sat, 09 Feb 2013 13:10:47 +0800, horseriver said: In one process ,what is the max number of opening file descriptor ? Can it be set to infinite ? In network programing ,what is the essential for the maximum of connections dealed per second In general, you'll find that number of file descriptors isn't what ends up killing you for high-performance network programming. What usually gets you are things like syn floods (either intentional ddos or getting slashdotted), because each time you do an accept() on an incoming connection you end up using userspace resources to handle the connection. So the *real* question becomes how many times per second is your box able to fork() off an httpd, do all the processing required, and close the connection? A secondary gotcha is that dying TCP connections end up stuck in FIN-WAIT and FIN-WAIT-2, And if you're trying to drive multiple 10G interfaces at line speed, it gets even more fun. Fortunately, for my application (high performance disk servers) the connections are mostly persistent, so it's only a problem of getting disks to move data that fast. :) pgpnFt8n4QjYM.pgp Description: PGP signature ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: MAX limit of file descriptor
On Mon, 11 Feb 2013 06:07:38 +0800, horseriver said: Actually , my question comes from network performance ,I want to know ,in per second ,the maximum of tcp connections that can be dealed with by my server. That will be *highly* dependent on what your server code does with each connection. A hello world reply and close socket will, of course, go lots faster than something that has to go contact an enterprise-scale database, do 3 SQL joins, and format the results. How can I do the test and calculate the connection number , Is it possible that my server can deal with 10k tcp connections per second? 10K/sec peaks can be achieved even on a laptop, assuming a dummy do-nothing service. Keeping that sustained for a real application will depend on the service time needed - if you have 20 CPUs in the box, and spread the load across all 20, you have to average under 2ms to service each request, which will be a killer if you have to go to disk at all for a request. At that point, the guys at Foundry will be more than happy to sell you a load-balancer so you can have a stack of 10 20-CPU servers each of which only handles 1K/sec and thus has a 20ms time budget. what is the relationship between this and throughput rate? Lots of tiny connections will totally suck at aggregate throughput, if for no other reason than TCP slow-start never gets a chance to really open the transmit window up. But in general, there is always a trade-off between transaction rate and throughput. Is there document that tells the best optimization of this ? best is defined by what your application actually needs. The best settings for my NFS server will be totally different than what the HTTP server 12 racks over needs... pgpwRsaM1hmdj.pgp Description: PGP signature ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Use of copy_to_user() and copy_from_user() functions
On Mon, Feb 11, 2013 at 5:25 PM, anish singh anish198519851...@gmail.comwrote: On Mon, Feb 11, 2013 at 4:51 PM, पारस bepa...@gmail.com wrote: Hi All, To read/write data to user-space from kernel-space we use copy_from_user() and copy_to_user() functions. What is the use of these function? Why kernel can't directly access user address and read/write on to it? what will happen if the user space process gets scheduled out while you were using it? copy_to/from_user should always be called from process context. So even if a process is scheduled out there is not impact, as when process schedule back in copying will resume to/from correct page. Can any one explain why kernel can't directly access the user-space address. Thanks ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Use of copy_to_user() and copy_from_user() functions
On Tue, Feb 12, 2013 at 9:24 AM, Chetan Nanda chetanna...@gmail.com wrote: On Mon, Feb 11, 2013 at 5:25 PM, anish singh anish198519851...@gmail.com wrote: On Mon, Feb 11, 2013 at 4:51 PM, पारस bepa...@gmail.com wrote: Hi All, To read/write data to user-space from kernel-space we use copy_from_user() and copy_to_user() functions. What is the use of these function? Why kernel can't directly access user address and read/write on to it? what will happen if the user space process gets scheduled out while you were using it? copy_to/from_user should always be called from process context. So even if a process is scheduled out there is not impact, as when process schedule back in copying will resume to/from correct page. because page fault will be triggered and the user space will be swapped in. That answers the original question. Can any one explain why kernel can't directly access the user-space address. Thanks ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: MAX limit of file descriptor
Hi! On 14:24 Mon 11 Feb , valdis.kletni...@vt.edu wrote: On Sat, 09 Feb 2013 13:10:47 +0800, horseriver said: ... In network programing ,what is the essential for the maximum of connections dealed per second ... So the *real* question becomes how many times per second is your box able to fork() off an httpd, do all the processing required, and close the connection? If you fork(), than this definitely will be your bottleneck (except the application does something even slower). Better use epoll+nonblocking i/o. -Michi -- programing a layer 3+4 network protocol for mesh networks see http://michaelblizek.twilightparadox.com ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
