Linux kernel live debugging, how it's done and what tools are used? -

-

what common , why not uncommon methods , tools used live debugging on linux kernel? know linus eg. against kind of debugging linux kernel or least , nothing has been done in sense in years, lot of time has passed since 2000 , interested if mentality has changed regarding linux project , current methods used live debugging on linux kernel @ moment(either local or remote)?

references walkthroughs , tutorials on mentioned techniques , tools welcome.

another option use ice/jtag controler, , gdb. 'hardware' solution used embedded systems,

but instance qemu offers similar features:

  • start qemu gdb 'remote' stub listens on 'localhost:1234' : qemu -s ...,

  • then gdb open kernel file vmlinux compiled debug informations (you can take this mailing list thread discuss unoptimization of kernel).

  • connect gdb , qemu: target remote localhost:1234

  • see you're live kernel:

    (gdb) #0  cpu_v7_do_idle () @ arch/arm/mm/proc-v7.s:77 #1  0xc0029728 in arch_idle () atarm/mach-realview/include/mach/system.h:36 #2  default_idle () @ arm/kernel/process.c:166 #3  0xc00298a8 in cpu_idle () @ arch/arm/kernel/process.c:199 #4  0xc00089c0 in start_kernel () @ init/main.c:713

unfortunately, user-space debugging not possible far gdb (no task list information, no mmu reprogramming see different process contexts, ...), if stay in kernel-space, that's quite conveniant.

  • info threads give list , states of different cpus

edit:

you can more details procedure in pdf:

debugging linux systems using gdb , qemu.


Comments

Post a Comment

Popular posts from this blog

javascript - Enclosure Memory Copies -

-
function myclass() { //lots , lots of vars , code here. this.bar = function() { //do numerous enclosed myclass vars } this.foo = function() { alert('hello'); //don't enclosed variables. } } each instance of myclass gets own copy of bar , foo, why prototyped methods use less memory. however, know more memory use of inner methods. it seems obvious me (1) below must true. agree? not distinct myclass instances have own distinct copies of bar, must have own distinct copies of myclass enclosure. (or else how bar method keep myclass variables straight on per instance basis?) now (2) question i'm after. since inner foo method doesn't use in myclass enclosure natural qustion is: javascript smart enough not keep myclass enclosure in memory use of foo? this depend entirely on implementation not language. naive implementations keep far more around others. answer true e.g. v8 (chrome's js engine) may not true spider...
Read more

php - Replacing tags in braces, even nested tags, with regex -

-
example preg_replace('/\{[a-za-z.,\(\)0-9]+\}/', 'replaced', 'lorem ipsum dolor sit {tag1({tag2()})}, consectetur adipiscing elit.'); the result: lorem ipsum dolor sit {tag1(replaced)}, consectetur adipiscing elit. question as can see "tag2" has been replaced, want replace "tag1" know how can this? (in cases might this: {tag1({tag2({tag3()})})}) , on.) btw using preg_replace_callback, easier show preg_replace here site can test code: http://www.spaweditor.com/scripts/regex/index.php you need add curly braces character set. here's pattern used: /\{[a-za-z.,\(\)\{\}0-9]+\}/ and here result: "lorem ipsum dolor sit replaced, consectetur adipiscing elit."
Read more