Re: kvm_amd BUG: unable to handle kernel NULL pointer dereference at 00000014

[Avi Kivity <avi@redhat.com>]

On 03/04/2011 12:34 AM, IVAN ANGELOV wrote:
> Hello,
> This provided dmesg message and kernel behavior appear when trying to
> run qemu-kvm with kvm_amd module. Without kvm_amd qemu-kvm runs fine
> but a slower. I managed to see that this happens with 2.6.38-rc6 ,
> 2.6.38-rc7 vanilla kernels compiled using kernel-package. OS ubuntu
> natty. Using the standard toolchain and gcc from ubuntu: gcc version
> 4.5.2 (Ubuntu/Linaro 4.5.2-3ubuntu3)
> I reverted to 2.6.37.2 linux kernel, compiled with the very same tools
> and machine I use qemu-kvm with kvm_amd module without any problems.
> If I can provide some extra info about that please let me know.
> This issue also appears with the kernel provided by the Ubuntu
> distribution: 2.6.38-5-generic-pae #32-Ubuntu SMP Tue Feb 22 17:48:56
> UTC 2011 i686 athlon i386 GNU/Linux , I suspect it is somehow related
> to the 2.6.38 kernel series.
> cpuinfo - phenom ii x4 955 mildly overclocked - 4 fields like this is
> the whole cpuinfo.


    c:    65 a1 14 00 00 00        mov    %gs:0x14,%eax

faults, gsbase == NULL.

But arch/x86/include/asm/percpu.h says:

#ifdef CONFIG_X86_64
#define __percpu_seg        gs
#define __percpu_mov_op        movq
#else
#define __percpu_seg        fs
#define __percpu_mov_op        movl
#endif


So we should be using %fs, not %gs.

-- 
error compiling committee.c: too many arguments to functionb