From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1Hgpdt-0003wW-Pn for qemu-devel@nongnu.org; Wed, 25 Apr 2007 18:07:17 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1Hgpds-0003ug-4C for qemu-devel@nongnu.org; Wed, 25 Apr 2007 18:07:17 -0400 Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Hgpds-0003uX-1E for qemu-devel@nongnu.org; Wed, 25 Apr 2007 18:07:16 -0400 Received: from wr-out-0506.google.com ([64.233.184.231]) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1HgpYC-0006Uo-6m for qemu-devel@nongnu.org; Wed, 25 Apr 2007 18:01:24 -0400 Received: by wr-out-0506.google.com with SMTP id i20so718597wra for ; Wed, 25 Apr 2007 15:01:23 -0700 (PDT) Message-ID: <5d649bdb0704251501x1998d8b0kaa67131dc2464ee5@mail.gmail.com> Date: Wed, 25 Apr 2007 17:01:22 -0500 From: "Neo Jia" In-Reply-To: <462FB4A1.3020704@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> <5d649bdb0704251007q771d7e92o288a4ea9319ced09@mail.gmail.com> <462FB4A1.3020704@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: > >> >> > 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. > > Did you redirect kgdb to ttyS1? Yes, I just redirect kgdb to ttyS1 but still nothing. But if I compiled with "CONFIG_KGDB_CONSOLE=y", it will show on the gdb console. Is a bug or wrong configuration? Thanks, Neo > > Jan > > > -- I would remember that if researchers were not ambitious probably today we haven't the technology we are using!