Re: Problems with GRUB and boot=on flag

[Anthony Liguori <anthony@codemonkey.ws>]

Alberto Treviño wrote:
> I am having a really weird problem.  I reported about it earlier (see 
> http://article.gmane.org/gmane.comp.emulators.kvm.devel/15884) thinking 
> the problem was with SCSI disks, but that's not the case.  Let me try 
> to explain.
>
> I have a drive that has GRUB and Linux.  If I run the following command, 
> it boots normally, even though the boot flag has been set to off:
>
>   qemu-system-x86_64 -m 256
>    -drive file=hd0.qcow2,if=ide,bus=0,index=0,media=disk,boot=off
>   

How did you install grub on this drive?  Is this a distro image or did 
you install grub yourself?

Regards,

Anthony Liguori

> If I run the following, qemu crashes when GRUB loads:
>
>   qemu-system-x86_64 -m 256
>    -drive file=hd0.qcow2,if=ide,bus=0,index=0,media=disk,boot=on
>
> Qemu reports the following when it crashes:
>
> exception 13 (33)
> rax 0000000000000000 rbx 0000000000000800 rcx 0000000000000000 rdx 
> 00000000000000e0
> rsi 00000000ffff7d98 rdi 000000000008f788 rsp 0000000000002018 rbp 
> 0000000000000001
> r8  0000000000000000 r9  0000000000000000 r10 0000000000000000 r11 
> 0000000000000000
> r12 0000000000000000 r13 0000000000000000 r14 0000000000000000 r15 
> 0000000000000000
> rip 0000000000000003 rflags 00033202
> cs 0000 (00000000/0000ffff p 1 dpl 3 db 0 s 1 type 3 l 0 g 0 avl 0)
> ds 0000 (00000000/0000ffff p 1 dpl 3 db 0 s 1 type 3 l 0 g 0 avl 0)
> es 0800 (00008000/0000ffff p 1 dpl 3 db 0 s 1 type 3 l 0 g 0 avl 0)
> ss 0000 (00000000/0000ffff p 1 dpl 3 db 0 s 1 type 3 l 0 g 0 avl 0)
> fs 0000 (00000000/0000ffff p 1 dpl 3 db 0 s 1 type 3 l 0 g 0 avl 0)
> gs 0000 (00000000/0000ffff p 1 dpl 3 db 0 s 1 type 3 l 0 g 0 avl 0)
> tr 0000 (fffbd000/00002088 p 1 dpl 0 db 0 s 0 type b l 0 g 0 avl 0)
> ldt 0000 (00000000/0000ffff p 1 dpl 0 db 0 s 0 type 2 l 0 g 0 avl 0)
> gdt fb1f2/30
> idt 0/3ff
> cr0 10 cr2 0 cr3 0 cr4 0 cr8 0 efer 0
> code: 53 ff 00 --> f0 53 ff 00 f0 53 ff 00 f0 53 ff 00 f0 53 ff 00 f0 53 
> ff 00 f0 53 ff 00 f0 53 ff 00 f0 a5 fe 00 f0 87 e9 00 f0 53 ff 00 f0 53 
> ff 00 f0 53 ff
> Aborted
>
> If I change the interface to SCSI and set the boot flag to off, Qemu 
> can't find a valid boot drive and does not boot.  If I change the 
> interface to SCSI and set the boot flag to on, I get the same crash.
>
> According to Anthony Liguori's original extboot post, "boot=on" turns on 
> the extboot code, so my problem is the combination of extboot and GRUB.  
> A response on my original post suggested this might be a real mode 
> issue.  However, it seems more of an extboot problem with some of the 
> calls from GRUB.
>
> What's the status of the extboot in C project?  Perhaps I could try that 
> to see if it fixes the problem.  Does anyone have any other 
> suggestions?
>
>