KDPeter?

See this patch:  https://lkml.org/lkml/2012/8/21/46 The author suggests: - p9_debug(P9_DEBUG_VFS, "%s -> %s (%s)\n", - dentry->d_name.name, st->extension, buffer); + p9_debug(P9_DEBUG_VFS, "%s -> %s (%.*s)\n", + dentry->d_name.name, st->extension, buflen, buffer); But what the heck does %.*s? And why buflen variable was added as parameter to p9_debug? What would be the output of the C program above: #include <stdio.h> void main () { int i; char *ab ="abcdefghi"; for (i = 0; i < 10; i++) printf ("%.*s\n", i, ab); } [peter@ace tmp]$ gcc test.c;./a.out a ab abc abcd abcde abcdef abcdefg abcdefgh abcdefghi Cool huh?

Thanks to my internship, on the raking of the number of patches accepted, only 10 people had sent more patches than me for the Kernel 3.7: The ranking:  http://www.remword.com/kps_result/3.7_petop.html \o/ Not bad for a newbie.

[peter@ace linux-next]$ git log |grep Author |grep peter.senna@gmail.com |wc -l 106 More than 100 patches accepted in the Linux Kernel. I'm happy with it but... Those are really simple patches and I need to work on finding more complex things to do. But I think I'm on the way...

I'm sending a lot of patches. Many are just being accepted. But there is one very interesting rejection. I have not received nack, and the patch was not directed to /dev/null. The maintainers are happy with the code, but they "really" want me to do a very specific commit message. See the full thread:  http://www.kernelhub.org/?p=2&msg=139304

From: Linus Torvalds <torvalds@linux-foundation.org> Newsgroups: fa.linux.kernel Subject: Re: [PATCH] Bugfix to commit Date: Tue, 23 Oct 2007 15:53:41 UTC Message-ID: <fa.kLlZ0+PrvWCrpZjNV34+zBLE2ro@ifi.uio.no> On Tue, 23 Oct 2007, Olaf Hering wrote: > > On Mon, Oct 22, Grant Likely wrote: > > > Olaf, do I have the correct solution here? > > Sure. Side note: I already applied that patch, but take a look at the commit message. That's right: I had to edit the message provided to make it readable. So I'll just take this opportunity to ask people that when they send bug-fixes, please try to make the subject line and message make sense for a *reader*, not for yourself (or even to me, although if it's readable to some generic person, it's hopefully readable to me too!). So a subject line of "Bugfix to commit <commit-sha-goes-here>" is obviously not a very nice one, if you're looking at the kernel co...

It is time to celebrate! I've submitted more than 100 patches to the Linux Kernel! Yeah! Yeah! See:  http://www.kernelhub.org/?p=7&dev=10021&mbox_type=2 Photo from:  http://www.sidneyrezende.com/noticia/16742+os+5+do+pit+stop++cinco+malandragens+de+nelson+piquet

Git is great! It really is. But you need to learn some secrets in order to use the full power. Two great resources: 1 - Pro git : Easy to read book that will make you very familiar with pro features of git. 2 -  AlBlue’s Blog : Great articles explaining standard and advanced features of git.

When you send a second version of the same patch, you may add a "v2" on the subject so it will look like: [PATCH v2] There is an option for git format-patch that does it: --subject-prefix="PATCH v2" More at: http://wireless.kernel.org/en/developers/Documentation/git-guide

" Sparse, the semantic parser, provides a compiler frontend capable of parsing most of ANSI C as well as many GCC extensions, and a collection of sample compiler backends, including a static analyzer also called "sparse". Sparse provides a set of annotations designed to convey semantic information about types, such as what address space pointers point to, or what locks a function acquires or releases. " There is more about SPARSE here . To check files that will be compiled with SPARSE: $ make C=1 To check all files with SPARSE, even the ones that will not be compiled: $ make C=2

To enable compiler warning messages to be printed during compilation, add W=1 on the make command line like: $ make W=1 drivers/media/dvb/frontends/stv090x.o See this for description of warning level options.

:-) http://git.linuxtv.org/media_tree.git?a=commitdiff;h=503d19495673583cd5a60cbe1d92317c7b9b7b65 http://git.linuxtv.org/media_tree.git?a=commitdiff;h=df1ec0272fd49aefaa4d3f80eee2d51d7c04ef02 http://git.linuxtv.org/media_tree.git?a=commitdiff;h=3e9e0ca227ea905b0d07f777c5316f44638428bf http://git.linuxtv.org/media_tree.git?a=commitdiff;h=3f7c0a69ab1181a0f5e4ead5d4b270d404c6465c http://git.linuxtv.org/media_tree.git?a=commitdiff;h=adb609666bbc53ddd12272fdf233fc8148e7bd0e

I've sent some patches for the linux-media mailing list. See: http://article.gmane.org/gmane.linux.drivers.video-input-infrastructure/49470 http://article.gmane.org/gmane.linux.drivers.video-input-infrastructure/49471 http://article.gmane.org/gmane.linux.drivers.video-input-infrastructure/49473 http://article.gmane.org/gmane.linux.drivers.video-input-infrastructure/49474 http://article.gmane.org/gmane.linux.drivers.video-input-infrastructure/49475 http://article.gmane.org/gmane.linux.drivers.video-input-infrastructure/49476 http://article.gmane.org/gmane.linux.drivers.video-input-infrastructure/49477 http://article.gmane.org/gmane.linux.drivers.video-input-infrastructure/49478 The first one was accepted two days ago. See: http://git.linuxtv.org/media_tree.git?a=commitdiff;h=cb4f6818f8534280954f6e2f2e0d59f337610ed1 My first patch will be applied to the 3.6 Kernel. :-D

https://www.linux.com/news/featured-blogs/191-linux-training/589034--brazilian-government-consultant-increases-knowledge-with-linux-training-opportunities

Installs Kernel package with debug options enabled, and debuginfo that will allow advanced Kernel tracing / profiling for oprofile and perf. For Kernel package: "kernel", not "kernel-debug". $ sudo yum install --enablerepo=fedora-debuginfo --enablerepo=updates-debuginfo kernel-debuginfo

Emdebian is a project that focus on thinner root filesystem than standard Debian. It is easy to spend 3.5 times less storage still being Debian. I've tested the Grip flavor of the project, more  here .

I've created a wiki page at Github to organize and share useful information I'm finding about Linux Kernel Development: https://github.com/petersenna/Kernel/wiki/How-to-start-Linux-Kernel-development

Can you believe that the code above can be optimized to run 14 times faster on Intel Core i7 CPU and to run 40 times faster on AMD Athlon X2? #define X_SIZE 60 #define Y_SIZE 30 int matrix[X_SIZE][Y_SIZE]; void initmatrix(void) { int x,y; for (x = 0; x < X_SIZE; ++x){ for (y = 0; y < Y_SIZE; ++y){ matrix[x][y] = -1; } } } void main() { initmatrix(); } Check my post:   C code optimization benchmark

The article: Writing device drivers in Linux: A brief tutorial Is a great starting point for Linux Kernel Development but it needs some simple updates. The first error you will find when compiling is: /home/peter/devel/kdpeter/2012/bricks/original-post/memory.c:3:26: fatal error: linux/config.h: No such file or directory compilation terminated. To fix, remove the line from the source code: #include <linux/config.h> Then some warnings: /home/peter/devel/kdpeter/2012/bricks/original-post/memory.c:28:3: warning: initialization from incompatible pointer type [enabled by default] /home/peter/devel/kdpeter/2012/bricks/original-post/memory.c:28:3: warning: (near initialization for ‘memory_fops.write’) [enabled by default] /home/peter/devel/kdpeter/2012/bricks/original-post/memory.c: In function ‘memory_write’: /home/peter/devel/kdpeter/2012/bricks/original-post/memory.c:110:17: warning: ignoring return value of ‘copy_from_user’, declared with attribute warn_unused...

Can you believe that a two line C source code can become a Linux module? $ cat simplest_module.c #include <linux/module.h> MODULE_LICENSE("GPL"); $ cat Makefile obj-m := simplest_module.o all: make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules clean: make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean Just "make". $ make To install your brand new bogus module: $ sudo insmod simplest_module.ko The lsmod command show that your module has been loaded: $ lsmod |grep simplest_module simplest_module          689  0 To remove the module: $ sudo rmmod simplest_module It is very simple to create a Linux Kernel Module. If you want more than a do nothing module, follow the links: Source:  Writing device drivers in Linux: A brief tutorial Recommended:  Writing a Simple USB Driver