Hello Peter & All,
I am trying to figure out a problem in qemu on aarch64 (with kvm
enabled). I have found this problem in many different versions of qemu
(v2.0.0-rc3/rc2/rc1/rc0, master 2d03b49), and I believe that either I am
missing something common in all of these versions or its a genuine bug
in qemu on aarch64.
The problem is triggered by virtqueue_notify() function (in
virtio_ring.c) from the guest kernel and fails in the
qemu_coroutine_new() while trying to do the swapcontext(&old_uc, &uc)
(see coroutine-ucontext.c:164). The sigsetjmp(old_env, 0) just before
the swapcontext() call seems to work fine, as it returns 0, and then we
invoke the swapcontext().
The host kernel reports:
"qemu-system-aar[596]: bad frame in sys_rt_sigreturn: pc=004462e0
sp=7f8020f000" and kills the qemu process due to segmentation fault. The
pc=004462e0 is for the coroutine_trampoline() but we don't actually
reach it, when this particular crash happens.
Just to give you an idea of the code I am talking about:
$~/qemu[master]$ git blame -L 159,166 coroutine-ucontext.c
00dccaf1 (Kevin Wolf 2011-01-17 16:08:14 +0000 159) makecontext(&uc,
(void (*)(void))coroutine_trampoline,
00dccaf1 (Kevin Wolf 2011-01-17 16:08:14 +0000 160)
2, arg.i[0], arg.i[1]);
00dccaf1 (Kevin Wolf 2011-01-17 16:08:14 +0000 161)
6ab7e546 (Peter Maydell 2013-02-20 15:21:09 +0000 162) /* swapcontext()
in, siglongjmp() back out */
6ab7e546 (Peter Maydell 2013-02-20 15:21:09 +0000 163) if
(!sigsetjmp(old_env, 0)) {
00dccaf1 (Kevin Wolf 2011-01-17 16:08:14 +0000 164)
swapcontext(&old_uc, &uc);
00dccaf1 (Kevin Wolf 2011-01-17 16:08:14 +0000 165) }
00dccaf1 (Kevin Wolf 2011-01-17 16:08:14 +0000 166) return &co->base;
My qemu configure/run commands are:
./configure --target-list=aarch64-softmmu \
--cross-prefix=aarch64-linux-gnu- \
--enable-fdt *--enable-kvm* --disable-werror \
--audio-drv-list="" --static
./qemu-system-aarch64 \
*-enable-kvm* -nographic -kernel Image \
-drive if=none,file=disk_oe64.img,id=fs \
-device virtio-blk-device,drive=fs \
-m 1024 -M virt -cpu host \
-append "earlyprintk console=ttyAMA0 mem=1024M rootwait
root=/dev/vda rw init=/bin/sh"
Any ideas/comments on how to resolve this issue?
Best Regards,
Hamayun
