From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1Hgl3P-0007TG-Tk for qemu-devel@nongnu.org; Wed, 25 Apr 2007 13:13:20 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1Hgl3O-0007T0-8l for qemu-devel@nongnu.org; Wed, 25 Apr 2007 13:13:18 -0400 Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Hgl3O-0007Sx-2F for qemu-devel@nongnu.org; Wed, 25 Apr 2007 13:13:18 -0400 Received: from nz-out-0506.google.com ([64.233.162.226]) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1Hgkxj-0004Yz-HX for qemu-devel@nongnu.org; Wed, 25 Apr 2007 13:07:27 -0400 Received: by nz-out-0506.google.com with SMTP id i11so847805nzi for ; Wed, 25 Apr 2007 10:07:27 -0700 (PDT) Message-ID: <5d649bdb0704251007q771d7e92o288a4ea9319ced09@mail.gmail.com> Date: Wed, 25 Apr 2007 12:07:26 -0500 From: "Neo Jia" In-Reply-To: <462F7D45.9000505@web.de> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <5d649bdb0704241811s301aa41bg2a93b8b4c923b023@mail.gmail.com> <462EEF7A.5040708@web.de> <5d649bdb0704242329x587bbfc4qe9feefd037e24f60@mail.gmail.com> <462EF6D5.1040504@web.de> <5d649bdb0704250854w3b7f413jae5241e9d229011e@mail.gmail.com> <462F7D45.9000505@web.de> Subject: [Qemu-devel] Re: How to debug Linux kernel on qemu with kgdb? Reply-To: qemu-devel@nongnu.org List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jan Kiszka Cc: qemu-devel@nongnu.org On 4/25/07, Jan Kiszka wrote: > Neo Jia wrote: > > On 4/25/07, Jan Kiszka wrote: > >> Neo Jia wrote: > >> > On 4/25/07, Jan Kiszka 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. > Could you show me the procedure you did? I just want to use this to learn kernel code. Thanks, Neo > > -- I would remember that if researchers were not ambitious probably today we haven't the technology we are using!