Hi, I make a video to introduce how to use KGTP debug the Linux kernel of Android. Please goto http://youtu.be/_UGN2j8Ctg0 or http://www.tudou.com/programs/view/FjkQ6HhPnfE/ see the English version. Or goto http://www.tudou.com/programs/view/qCumSPhByFI/ or http://youtu.be/9YMpAvsl37I see the Chinese version.
Thanks, Hui On Wed, May 8, 2013 at 5:41 PM, Hui Zhu <teawa...@gmail.com> wrote: > Hi guys, > > KGTP (http://code.google.com/p/kgtp/) is a flexible, lightweight and > realtime Linux debugger and tracer. > To use it, you don't need patch or rebuild the Linux kernel. Just > build KGTP module and insmod it is OK. > > Please go to http://code.google.com/p/kgtp/wiki/HOWTO or > http://code.google.com/p/kgtp/wiki/HOWTO (Chinese) to get more info > about howto use KGTP. > > Please goto > https://code.google.com/p/kgtp/wiki/HOWTO#Table_of_different_between_GDB_debug_normal_program_and_KGTP > or https://code.google.com/p/kgtp/wiki/HOWTOCN#GDB调试普通程序和KGTP的区别表 > (Chinese) get the table of different between GDB debug normal program > and KGTP if you have experience using GDB debug normal program. > > Now, KGTP 20130508 release. > You can get the package for it from > http://kgtp.googlecode.com/files/kgtp_20130508.tar.bz2 > or > svn co https://kgtp.googlecode.com/svn/tags/20130508 > > The main change of this release is complete the support of > while-stepping. KGTP can let Linux kernel do single step now. > Please note that while-stepping is just support by X86 and X86_64 now. > Howto use while-stepping: > while-stepping is a special tracepoint action that include some actions with > it. > When tracepoints that its actions include "while-stepping n" execute, > it will do n times single steps and executes the actions of > while-stepping. For example: > trace vfs_read > #Because single step will make system slow, so use passcount or > condition to limit the execution times of tracepoint is better. > passcount 1 > commands > collect $bt > collect $step_count > #do 2000 times single steps. > while-stepping 2000 > #Following part is actions of "while-stepping 2000". > #Because step maybe execute to other functions, so does not > access local variables is better. > collect $bt > collect $step_count > end > end > You can switch KGTP to replay mode to select all the traceframe of a > while-stepping tracepoint with GDB execution and reverse-execution > commands. For example: > Use tfind select one the traceframe of a while-stepping tracepoint. > (gdb) tfind > Found trace frame 0, tracepoint 1 > #0 vfs_read (file=0xffff8801f7bd4c00, buf=0x7fff74e4edb0 <Address > 0x7fff74e4edb0 out of bounds>, count=16, > pos=0xffff8801f4b45f48) at /build/buildd/linux-3.2.0/fs/read_write.c:365 > 365 { > Following commands will swith KGTP to replay mode. > > (gdb) monitor replay > (gdb) tfind -1 > No longer looking at any trace frame > #0 vfs_read (file=0xffff8801f7bd4c00, buf=0x7fff74e4edb0 <Address > 0x7fff74e4edb0 out of bounds>, count=16, > pos=0xffff8801f4b45f48) at /build/buildd/linux-3.2.0/fs/read_write.c:365 > 365 { > Then you can use execution commands. > > (gdb) n > 368 if (!(file->f_mode & FMODE_READ)) > (gdb) p file->f_mode > $5 = 3 > Set breakpoints (Just valid in replay mode, will not affect Linux > kernel execution). > > (gdb) b 375 > Breakpoint 2 at 0xffffffff81179b75: file > /build/buildd/linux-3.2.0/fs/read_write.c, line 375. > (gdb) c > Continuing. > > Breakpoint 2, vfs_read (file=0xffff8801f7bd4c00, buf=0x7fff74e4edb0 > <Address 0x7fff74e4edb0 out of bounds>, count=16, > pos=0xffff8801f4b45f48) at /build/buildd/linux-3.2.0/fs/read_write.c:375 > 375 ret = rw_verify_area(READ, file, pos, count); > (gdb) s > rw_verify_area (read_write=0, file=0xffff8801f7bd4c00, > ppos=0xffff8801f4b45f48, count=16) > at /build/buildd/linux-3.2.0/fs/read_write.c:300 > 300 inode = file->f_path.dentry->d_inode; > Use reverse-execution commands. > > (gdb) rs > > Breakpoint 2, vfs_read (file=0xffff8801f7bd4c00, buf=0x7fff74e4edb0 > <Address 0x7fff74e4edb0 out of bounds>, count=16, > pos=0xffff8801f4b45f48) at /build/buildd/linux-3.2.0/fs/read_write.c:375 > 375 ret = rw_verify_area(READ, file, pos, count); > (gdb) rn > 372 if (unlikely(!access_ok(VERIFY_WRITE, buf, count))) > GDB commands tstart, tfind or quit can auto close the replay mode. > > Please goto > https://code.google.com/p/kgtp/wiki/HOWTO#Use_while-stepping_let_Linux_kernel_do_single_step > or https://code.google.com/p/kgtp/wiki/HOWTOCN#使用while-stepping让Linux内核做单步 > (Chinese version) get more info about it. > > Please goto http://code.google.com/p/kgtp/wiki/UPDATE get more info > about this release. > > According to the comments of Christoph, Geoff and Andi. I make lite > patch for review. Please goto https://lkml.org/lkml/2012/5/9/90 to > see it. > > Thanks, > Hui -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
