[Qemu-devel] 64-bit Qemu and remote GDB to Kernel Error

[Matt Davis]

Hello,
I am trying to debug a 32-bit linux kernel with gdb and qemu.  My qemu
runs the 64-bit kernel as:
address@hidden> qemu -kernel vmlinuz -S -s  (not using kvm).  If I try with
kvm the breakpoint does not even seem to get tripped.

And then I fire up gdb on my 64-bit machine (the same one running
qemu).  And I set my "target remote :1234" and set a breakpoint.
Anyways, I seem to catch my breakpoint, but when it should be tripping
I get the following error :
Remote 'g' packet reply is too long: <data>

I have done similar stuff fine on a 32bit machine running both 32-bit
qemu and a 32-bit kernel.  I have also googled, and this seems to not
be uncommon (circa 2008).  But I have not seen anything recently
regarding this.  Should it be working now?  If not is there a better
solution?  I tried, on my 64bit machine, to run a 32-bit kernel in
qemu, but my breakpoints were still not tripping in gdb.  Yes, the
kernel did have debugging flags built in.  I also forced the gdb
architecture to use "set arch i386:x86-64" not much difference if I
recall.

The following thread had similar issues when trying to set a break in
64 bit land, but not mention of the error I reported above.  These
possibly cold be related:
http://lists.gnu.org/archive/html/qemu-devel/2008-05/msg00287.html

-Matt