tag:blogger.com,1999:blog-6952446304140363640Mon, 09 Sep 2024 04:32:12 +0000modulesC ProgrammingC tricksINIT_RLIMITSRLIM_NLIMITScontainer_ofcurrent processcurrent_thread_info()getpid()getrlimitinitinit_taskkernelkernel stacklimits.conflinked listlinuxlinux kernel 2.6list_entrymicrokernelmonolithicnew moduleoffset_ofpidprintk()processresource limitsresource.hrlimrlimitsetrlimitstruct list_headstructofswappersyslogtask_structtgidthread_infothread_unionulimitPeeping into working of Linux kernel: its design, data structures, functions, architecture, and approach.http://insidelinuxkernel.blogspot.com/noreply@blogger.com (NeverMind)Blogger9125tag:blogger.com,1999:blog-6952446304140363640.post-2288349532641871868Thu, 30 Apr 2009 14:20:00 +00002009-05-03T18:48:48.441+05:30C ProgrammingC trickscontainer_oflinked listlinux kernel 2.6list_entryoffset_ofstruct list_headstructofPrescript:In addition to explaining yet another ingredient of Linux kernel, this post implicitly covers some useful C programming techniques. A reader with the thought “...perhaps I can use this in my xyz program...” can apply these techniques to everyday programming.---Now that we’ve seen an important data structure of the Linux kernel, it’s best to visit one of the most fundamental building http://insidelinuxkernel.blogspot.com/2009/04/linux-kernel-linked-list.htmlnoreply@blogger.com (NeverMind)0tag:blogger.com,1999:blog-6952446304140363640.post-1056667537160296134Tue, 09 Dec 2008 09:44:00 +00002009-04-15T18:01:23.336+05:30initINIT_RLIMITSinit_tasklimits.confswapperulimitTo continue further our discussion of what are process resource limits, let’s see some real figures. Try putting following two printk() statements in FirstModuleSource.c posted here.printk (KERN_INFO "Process Name: %s", current -> comm); printk(KERN_INFO "current limit- # processes: %ul\n", current -> rlim[RLIMIT_NOFILE].rlim_cur);printk(KERN_INFO "maximum limit- # processes: %ul\n", current -> http://insidelinuxkernel.blogspot.com/2008/12/do-you-know-your-limits.htmlnoreply@blogger.com (NeverMind)0tag:blogger.com,1999:blog-6952446304140363640.post-7851849499104324287Sat, 22 Nov 2008 10:54:00 +00002008-11-22T17:28:45.621+05:30getrlimitresource limitsresource.hrlimRLIM_NLIMITSrlimitsetrlimitHaving seen the task_struct structure representing a process in kernel, in this post we shall discuss one very important field of task_struct, named rlim (#line 460 in the snapshot of sched.h in last post). A process can never access the system resources how much ever it wants. Linux kernel imposes limits on the amount of resources a process is allowed to use, so that a single process cannot http://insidelinuxkernel.blogspot.com/2008/11/process-resource-limits.htmlnoreply@blogger.com (NeverMind)0tag:blogger.com,1999:blog-6952446304140363640.post-8984283638925675301Tue, 29 Jul 2008 05:18:00 +00002008-08-13T11:08:37.186+05:30current processcurrent_thread_info()getpid()kernel stackpidprocesstask_structtgidthread_infothread_union<!--[if gte mso 9]> Normal 0 false false false MicrosoftInternetExplorer4 <![endif]--><!--[if gte mso 9]> <![endif]--> <!-- /* Font Definitions */ @font-face {font-family:Georgia; panose-1:2 4 5 2 5 4 5 2 3 3; mso-font-charset:0; mso-generic-font-family:roman; mso-font-pitch:variable; mso-font-signature:647 0 0 0 159 0;} /* Style http://insidelinuxkernel.blogspot.com/2008/08/kernel-process-data-structures.htmlnoreply@blogger.com (NeverMind)2tag:blogger.com,1999:blog-6952446304140363640.post-9098446128928893055Mon, 21 Jul 2008 08:32:00 +00002009-04-15T17:57:03.996+05:30printk()syslogIn the example myFirstModuleSource.c of Writing the First Kernel Module, I used printk() just as another name of printf(). In this post I note the differences between the two, and the way Linux kernel uses it. <?xml:namespace prefix = o />At the first glance, the only difference between printk() and printf() is the way the two functions are called. However, this single difference causes all the http://insidelinuxkernel.blogspot.com/2008/07/there-is-something-about-printk.htmlnoreply@blogger.com (NeverMind)0tag:blogger.com,1999:blog-6952446304140363640.post-1630886272861879733Sat, 19 Jul 2008 10:33:00 +00002008-08-13T14:28:32.282+05:30modules <!-- @page { size: 8.27in 11.69in; margin: 0.79in } P { margin-bottom: 0.08in } --> Let’s now see how to compile the module program shown in previous post. We shall write a Makefile to make the procedure of compilation simpler. Below is a ‘template’ of a Makefile, which I use to compile my modules. The description follows. #################################################http://insidelinuxkernel.blogspot.com/2008/07/compiling-and-inserting-first-kernel.htmlnoreply@blogger.com (Unknown)0tag:blogger.com,1999:blog-6952446304140363640.post-2723266573774289361Tue, 15 Jul 2008 16:30:00 +00002008-08-12T14:00:13.586+05:30new module<!--[if gte mso 9]> Normal 0 false false false MicrosoftInternetExplorer4 <![endif]--><!--[if gte mso 9]> <![endif]--><!--[if !mso]> st1\:*{behavior:url(#ieooui) } <![endif]--> <!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0in; margin-bottom:.0001pt; mso-pagination:widow-orphan; http://insidelinuxkernel.blogspot.com/2008/07/how-to-write-module.htmlnoreply@blogger.com (Unknown)0tag:blogger.com,1999:blog-6952446304140363640.post-308398997160029951Wed, 25 Jun 2008 07:21:00 +00002008-07-30T11:30:20.375+05:30kernellinuxmicrokernelmodulesmonolithicTypically kernel literature start with the words like modules, microkernels etc. Lets quickly run over these to set the context right for reading.Often the terms operating system and kernel are confused because the two terms are used interchangeably in many books. But actually there is a difference: kernel is just one part of operating system, other parts being device drivers, user interface etc.http://insidelinuxkernel.blogspot.com/2008/06/os-kernel-and-modules.htmlnoreply@blogger.com (NeverMind)0tag:blogger.com,1999:blog-6952446304140363640.post-7685849140218863941Thu, 19 Jun 2008 14:05:00 +00002008-07-28T12:20:31.504+05:30The Linux kernel is such a nice example of a well defined, cleanly interfaced, layered, modular designed system software. One may look at the kernel code to see how object oriented-ness is realized in C programming, a language which does not directly support this feature.The subject of linux kernel is so deep and vast but equally interesting. For a beginner like me, it opens windows of http://insidelinuxkernel.blogspot.com/2008/06/wish-me-luck.htmlnoreply@blogger.com (NeverMind)0