Neo Jia wrote: > On 4/25/07, Jan Kiszka <[EMAIL PROTECTED]> wrote: >> Neo Jia wrote: >> > On 4/25/07, Jan Kiszka <[EMAIL PROTECTED]> wrote: >> >> Neo Jia wrote: >> >> > hi, >> >> > >> >> > I am trying to use debug kgdb patched linux kernel on my qemu. Both >> >> > the native and target platform are IA32. I am wondering if there is >> >> > anyone can show me the procedure? >> >> >> >> Yep, see >> https://mail.gna.org/public/xenomai-core/2006-09/msg00202.html >> >> >> >> (BTW, I think that kgdb bug is still unfixed - I never got a >> feedback.) >> > >> > I can connect gdb through /dev/pts/XX. My qemu is lanuched by >> > >> > qemu -nographic -hda linux.img -kernel >> > ./2.6.15.5-kgdb/vmlinuz-2.6.15.5-kgdb -serial pty -append "kgdbwait >> > console=ttyS0 root=/dev/hda sb=0x220,5,1,5 ide2=noprobe ide3=noprobe >> > ide4=noprobe ide5=noprobe" >> > >> > Do you know where can I get the console output? >> > >> >> Use "... -serial stdio -serial pty ..." and attached kgdb to the second >> serial port (I think to recall that is default anyway). The first one is >> then used for the kernel console. >> >> > I would like to work out kgdb + qemu to debug linux kernel. >> >> ??? So you really want to debug the kernel when kgdb is applied, ie. >> actually debug kgdb? If you only intend to debug the kernel itself, qemu >> -s + gdb is enough. > > Jan, > > I just would like to debug kernel itself. I have tried qemu -s + gdb > but it keeps > getting "apic_timer_interrupt" when I am using "n" command. > > The following is the output: > >> gdb vmlinux > GNU gdb 6.5.50.20060621-cvs > Copyright (C) 2006 Free Software Foundation, Inc. > GDB is free software, covered by the GNU General Public License, and you > are > welcome to change it and/or distribute copies of it under certain > conditions. > Type "show copying" to see the conditions. > There is absolutely no warranty for GDB. Type "show warranty" for details. > This GDB was configured as "i686-pc-linux-gnu"...Using host > libthread_db library "/lib/tls/libthread_db.so.1". > > (gdb) target remote localhost:1234 > Remote debugging using localhost:1234 > 0x0000fff0 in ?? () > warning: shared library handler failed to enable breakpoint > (gdb) c > Continuing. > > Program received signal SIGINT, Interrupt. > default_idle () at include/asm/bitops.h:252 > 252 return ((1UL << (nr & 31)) & (addr[nr >> 5])) != 0; > (gdb) b sys_ex > sys_execve sys_exit sys_exit_group > (gdb) b sys_execve > Breakpoint 1 at 0xc0101ac1: file arch/i386/kernel/process.c, line 791. > (gdb) c > Continuing. > > Breakpoint 1, sys_execve (regs= > {ebx = 135197704, ecx = 135197864, edx = 135244936, esi = > 135197704, edi = 135197704, ebp = -1079176984, eax = 11, xds = 123, > xes = 123, orig_eax = 11, eip = -1208835017, xcs = 115, eflags = 582, > esp = -1079177012, xss = 123}) > at arch/i386/kernel/process.c:791 > 791 filename = getname((char __user *) regs.ebx); > (gdb) n > 0xc0103666 in apic_timer_interrupt () at include/asm/current.h:9 > 9 {
That's normal. You stopped the kernel in sys_execve with interrupts enabled. When continuing, qemu replays any pending interrupts, here the timer. Thus your next instruction is not in sys_execve, but in the interrupt handler. You can try finish then and hope that you will return to the next line in sys_execve, or you put another breakpoint at the next interesting spot and just issue continue. Jan PS: Using kgdb from inside qemu should work (at least it once did for me), but it is really sloooow.
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