Contributing to Kernel Networking stack
I have strong desire to contribute to kernel networking stack. What is the most effective way to do some pretty significant changes (bug fixes, feature addition) in less time. All you kernel gurus please guide me. I have read UTLK pretty well (I don't say I understood it all, but for ex. I know where which locking mechanism is used, what is mem barrier and how it is implemented etc.) Regards, Shraddha ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Updating the kernel
Is it possible to keep the kernel updated to upstream without ever rebooting the system ? Ksplice ?? Regards, Shraddha ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Analyzing Kernel call traces.
Any good tutorial for analyzing kernel call traces ? I want to know what is the meaning of everything that appears in the call trace and get to the exact cause of the problem. Thanks for the noble cause of sharing knowledge. Regards, Shraddha ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Couple of questions on OOM trace.
Here is the OOM trace header : Out of memory: Kill process 5374 (min_free_kbytes) score 944 or sacrifice child Killed process 5374 (min_free_kbytes) total-vm:30495360kB,anon-rss:20155328kB, file-rss:64kB min_free_kbytes invoked oom-killer: gfp_mask=0x200da, order=0, oom_score_adj=0 min_free_kbytes cpuset=/ mems_allowed=0 -- I understand that in this case free pages has gone below min_pages(1). Couple of questions based on these 4 lines : (1) I googled a lot but I am not able to find the meaning of 'score 994' , anon-rss and file-rss ? (2) In my understanding gfp_mask is relevant here to know from which Zone the memory allocation was tried , but failed - right ? (3) What do order and oom_score_adj signify here ? Regards, Shraddha (1) http://dd.qc.ca/people.redhat.com/kernel/min_free_kbytes.html ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
process context value
I was reading about PowerPC-64 address translation and stumbled upon a term 'process context value' - googled but could not find much details about this - please help. regards, Shraddha ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Major/minor numbers
Does the max number of devices supported by Linux limited by major minor number ? Can you please give me some pointers regarding this. -- Shraddha ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Examples of Per-CPU Variables in Kernel source
I was reading about Per-CPU Variables from UTLK. Where are such variables used in the kernel source code - example. -- Shraddha ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Examples of Per-CPU Variables in Kernel source
On Sun, 2013-02-24 at 14:07 +0530, Shraddha Kamat wrote: I was reading about Per-CPU Variables from UTLK. Where are such variables used in the kernel source code - example. -- Shraddha got a very nice article on Per-CPU variable here - http://www.makelinux.net/ldd3/chp-8-sect-5 that clears up my doubt. ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
atomic operations
what is the relation between atomic operations and memory alignment ? I read from UTLK that an unaligned memory access is not atomic please explain me , I am not able to get the relationship between memory alignment and atomicity of the operation. ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
barrier()
#define barrier() asm volatile( ::: memory) What exactly volatile( ::: memory) doing here ? I was referring to gnu as (ver 2.14) manual but could not get much clue about this assembly construct - any pointers ? ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: /root/.debug/ ... ?
On Tue, 2013-02-05 at 10:14 +, Anuz Pratap Singh Tomar wrote: 8a73921f509a12a1cd7fb49dd8d1203197294c9e # git show 8a73921f509a12a1cd7fb49dd8d1203197294c9e fatal: bad object 8a73921f509a12a1cd7fb49dd8d1203197294c9e -- Shraddha ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
pr_info not printing message in /var/log/messages
I was looking at http://stackoverflow.com/questions/8090944/printk-not-working-for-kernel-debgugging Initially it was - # cat /proc/sys/kernel/printk 7 4 1 7 Then i did - # echo 7 7 /proc/sys/kernel/printk # cat /proc/sys/kernel/printk 7 7 1 7 # sysctl -a | grep printk kernel.printk = 7 7 1 7 kernel.printk_delay = 0 kernel.printk_ratelimit = 5 kernel.printk_ratelimit_burst = 10 still I the pr_info (hello, world); message doesn't get printed to /var/log/messages. please give me some hints as to resolve this issue. -- Shraddha ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Kernel DSO ?
What is a kernel DSO ? I encountered it while I was reading perf code. -- shraddha ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
/root/.debug/ ... ?
Might be a silly question - but since I am a newbie I am trying to understand the reason for existance for most of the stuff that I find while reading the code --- here is my question -- I see that there is a directory - /root/.debug/lib/modules/3.8.0-rc5 +/kernel/net/8021q/8021q.ko/8a73921f509a12a1cd7fb49dd8d1203197294c9e Why is this directory here for ? What is this file 8a73921f509a12a1cd7fb49dd8d1203197294c9e ? -- Shraddha ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
schedular / NUMA projects to work on
I am interested to work on schedular/ NUMA projects but I don't have high end hardware to test the results - is there any way (like not sure but - virtualization etc.) I can do it on a quad core single socket machine that I have. -- Shraddha ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Best way to configure Linux kernel for a machine
I normally do the kernel configuration on my machine like this - * copy the distro configuration file to the kernel dir * make menuconfig (answer Y's/N's/M's) Normally keep return key pressed for default answers * then do the actual kernel compilation Now, I know that this is not a clean way to do the kernel compilation (although it has worked for me for thousands of times that I have compiled and successfully booted up with the kernel - without any issues - whatsoever !) But this time , I am bent upon coming up with a configuration specifically targeted to my machine. What is the best way to do this ? Also, while creating a initrd image # mkinitrd /boot/initramfs.img 3.8.0-rc3+ -f ERROR: modinfo: could not find module ipt_MASQUERADE ERROR: modinfo: could not find module iptable_nat ERROR: modinfo: could not find module nf_nat ERROR: modinfo: could not find module snd_hda_codec_intelhdmi ERROR: modinfo: could not find module joydev I got the above errors - I know how to resolve these errors , but want to understand why in the first place mkinitrd should complain in the first place ?? Thanks list for help for all these years. -- Shraddha ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: what does this error mean?
On Fri, 2013-01-04 at 13:33 +0800, John Smith wrote: Not enough room for program headers Check this out - http://www.delorie.com/gnu/docs/binutils/ld_48.html search for 'Not enough room for program headers' -- Shraddha ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Fedora kernel rpmbuild query
Hi List, I do the following on Fedora kernel src rpm : (1) rpm -ivh kernel-xxx.rpm (2) Go to ~/rpmbuild/SPECS dir (2) rpmbuild -bp kernel.specs --nodeps then in the ~/rpmbuild/BUILD/ dir I get kernel-xxx dir where in there are two source dir - (1) linux-xxx A (2) vanilla-xxx B Why are these two dir created - How do I use the configuration file /boot/config-xxx to build vmlinuz and initrd image ? Which dir A or B sould I use for building ? -- Shraddha ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Fedora kernel rpmbuild query
On Wed, 2012-12-26 at 14:29 +0530, Pritam Bankar wrote: Hi Shraddha, Please find my comments below, On Wed, Dec 26, 2012 at 1:35 PM, Shraddha Kamat sh200...@gmail.com wrote: Hi List, I do the following on Fedora kernel src rpm : (1) rpm -ivh kernel-xxx.rpm (2) Go to ~/rpmbuild/SPECS dir (2) rpmbuild -bp kernel.specs --nodeps then in the ~/rpmbuild/BUILD/ dir I get kernel-xxx dir where in there are two source dir - (1) linux-xxx A (2) vanilla-xxx B Why are these two dir created - How do I use the configuration file /boot/config-xxx to build vmlinuz and initrd image ? Directory B is vanilla kernel source which is standard kernel source. This is a same source which is available on kernel.org Directory A is actually for source which has been modified by user. In this case it will have patches from FEDORA above standard kernel from kernel.org. To build vmlinuz and initrd image copy /boot/config-xxx to Directory A (linux-xxx) and run sudo make oldconfig then follow normal compilation steps Which dir A or B sould I use for building ? You should be using directory A Sure, I guessed so and did this only, but just to confirm I posted in the list It worked ! Thank you very much for you reply! -- Shraddha ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies Thanks, Pritam ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Fedora kernel rpmbuild query
On Wed, 2012-12-26 at 14:50 +0530, devendra.aaru wrote: On Wed, Dec 26, 2012 at 1:35 PM, Shraddha Kamat sh200...@gmail.com wrote: Hi List, I do the following on Fedora kernel src rpm : (1) rpm -ivh kernel-xxx.rpm (2) Go to ~/rpmbuild/SPECS dir (2) rpmbuild -bp kernel.specs --nodeps then in the ~/rpmbuild/BUILD/ dir I get kernel-xxx dir where in there are two source dir - (1) linux-xxx A (2) vanilla-xxx B Why are these two dir created - How do I use the configuration file /boot/config-xxx to build vmlinuz and initrd image ? Which dir A or B sould I use for building ? i dunno why you are doing these things, all these look hard path. this is what i do: take new kernel from ftp.kernel.org or git.kernel.org. make defconfig make -j10 make modules_install make install I am not building upstream kernel - this is a kernel supplied by the distro with custom patches. there are some gliches to it, say you have to select the filesystems correctly like if you have ext2, in .config enable CONFIG_EXT2_FS=y or what ever the filesystem currently you have. and your ethernet driver (as of now compile the ethernet drivers as modules) (make menuconfig then networking then ethernet ) same with the wireless drivers too, (make menuconfig then networking then wireless ) the names i mentioned may change but please go through google once posting here :) Thank you very much for you reply. thanks, -- Shraddha ___ 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
Difference x86 and x86_64
I used x86 - bzImage to boot my machine and 'uname -a' shows this :- Linux phx4 3.7.1 #3 SMP Sun Dec 23 16:28:20 IST 2012 x86_64 x86_64 x86_64 GNU/Linux where I see x86_64 arch (and not x86_64) ??? What is the difference between arch/x86 and arch/x86_64 ? -- Shraddha ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Question regarding patches
Sorry if this is not relevant to kernel. But since I am patching the kernel - Please consider this as a uber beginner question to ask on this mailing list - forgive me for that. Now my question is - What @@ -321,7 +321,8 @@ mean in this snippet from the patch - diff --git a/exec.h b/exec.h index 722c620..6abb687 100644 --- a/exec.h +++ b/exec.h @@ -321,7 +321,8 @@ static void acct_arg_size(struct linux_binprm *bprm, unsigned long pages); -- Shraddha ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Why do { // do something ; } while (0); ?
I notice
do {
// do something 1 ;
// do something 2 ;
...
} while (0);
being used everywhere in the kernel code
I just can't guess of any use of this other
than executing couple of C statements together ?
Is there any special purpose of doing this ??
Sorry of such a silly question - I am just trying
to learn kernel hacking basics.
-- Shraddha
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double exclamation mark meaning ?
Hi, # define likely(x) __builtin_expect(!!(x), 1) # define unlikely(x)__builtin_expect(!!(x), 0) I see these !! in the above expressions. Please explain me the meaning of those double exclamations. What is their significance ? -- Shraddha ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Best and fastest way to understand kernel subsystem ?
What is the best (and the fastest ) way to understand a kernel subsystem ( for e.g., filesystem , Networking .. etc.) -- Shraddha ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
