[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Qemu-devel] Re: Debugging a 64-bit kernel in qemu
From: |
Jan Kiszka |
Subject: |
[Qemu-devel] Re: Debugging a 64-bit kernel in qemu |
Date: |
Mon, 03 Jan 2011 12:15:01 +0100 |
User-agent: |
Mozilla/5.0 (X11; U; Linux i686 (x86_64); de; rv:1.8.1.12) Gecko/20080226 SUSE/2.0.0.12-1.1 Thunderbird/2.0.0.12 Mnenhy/0.7.5.666 |
Am 03.01.2011 11:27, Markus Duft wrote:
> Hi!
>
> I have been playing a little with this: I'm writing a kernel for both x86 and
> x86-64. While doing so, i'd like to debug the kernel using qemu (and it's gdb
> stub) and gdb. This worked very well until qemu-0.11.1 (gdb version does not
> seem to play any role...). From there on, debugging the 64 bit version no
> longer works. My sessions look like this with qemu-0.13.50 (and any version
> above 0.11.1, actually...):
>
> address@hidden /big/Privat/osdev/tachyon2 $ x86_64-pc-linux-gnu-gdb
> .build/x86_64/x86_64-tachyon
> GNU gdb (GDB) 7.2.50.20110103-cvs
> [snip]
> Reading symbols from
> /big/Privat/osdev/tachyon2/.build/x86_64/x86_64-tachyon...done.
> (gdb) target remote:1234
> Remote debugging using :1234
> 0x0000000000000000 in ?? ()
> (gdb) b boot
> Breakpoint 1 at 0xffffffff80119000: file
> /big/Privat/osdev/tachyon2/core/tachyon.boot/Entry.cc, line 25.
> (gdb) c
> Continuing.
> Remote 'g' packet reply is too long:
> 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
>
> 0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
> 000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000801f0000
> (gdb) quit
>
> actuallly, i _can_ debug the kernel, nut only until the long mode switch
> occurs. after this point: no luck... :[
>
> now for the questions:
>
> 1) is this a problem with qemu or was qemu "fixed" and gdb has a problem?
> (that's why i CCd the gdb list ;)).
> 2) is there any plan to fix this issue?
> 3) is there some kind of workaround i can use (i'd be happy with an
> ugly/unsupported patch too, since i build all my stuff myself ;)).
You see the effects of a workaround in qemu for gdb shortcomings on x86.
See e.g. http://thread.gmane.org/gmane.comp.emulators.qemu/80327, there
should be some threads on the gdb list as well.
Jan
signature.asc
Description: OpenPGP digital signature