Direct kernel boot without harddrive image

Direct kernel boot without harddrive image

[Daire Byrne]

Hi,

Admittedly this looks more like a Qemu issue but it effects KVM too which is all I'm interested in. I have a kernel and initrd which contains a mini busybox root environment which I want to boot directly using -kernel and -initrd. Now this works fine on first start but if I reboot within the system QEMU crashes out on the next run. I used "-hda /dev/zero" instead of a HD image. When qemu crashes after the reboot it dumps something like this:

[root@sys422 ~]# /usr/bin/qemu-kvm -m 1024 -smp 1 -name fedora3 -kernel vmlinuz-current -initrd initrd-diskless.img -append 'init=/init ramdisk_size=65536 root=/dev/ram0 rw' -hda /dev/zero
qemu: loading initrd (0x282bde bytes) at 0x000000001fd7d000
exception 13 (33)
rax 000000000000b141 rbx 0000000000000100 rcx 0000000000000000 rdx 0000000000000100
rsi 0000000000000000 rdi 0000000000000000 rsp 000000000000fff2 rbp 0000000000000000
r8 0000000000000000 r9 0000000000000000 r10 0000000000000000 r11 0000000000000000
r12 0000000000000000 r13 0000000000000000 r14 0000000000000000 r15 0000000000000000
rip 000000000000002c rflags 00033017
cs 1020 (00010200/0000ffff 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 1000 (00010000/0000ffff p 1 dpl 3 db 0 s 1 type 3 l 0 g 0 avl 0)
ss 1000 (00010000/0000ffff p 1 dpl 3 db 0 s 1 type 3 l 0 g 0 avl 0)
fs 1000 (00010000/0000ffff 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 0080 (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 fb812/30
idt 0/3ff
cr0 10 cr2 0 cr3 0 cr4 0 cr8 0 efer 0
code: 00 d0 d7 1f de 2b 28 00 00 00 00 00 00 fe 00 00 00 00 02 00 --> ff ff ff 1f e8 cd 0c eb 0b 90 90 90 90 90 90 90 90 90 90 90 00 00 00 00 00 00 00 00 00 00

Is direct kernel booting just not really supported properly or is it just to do with Qemu forgetting about the direct boot kernel/initrd after a reboot?

Daire

Re: Direct kernel boot without harddrive image

[Avi Kivity]

Daire Byrne wrote:
> Is direct kernel booting just not really supported properly or is it just to do with Qemu forgetting about the direct boot kernel/initrd after a reboot?
>   

Direct kernel booting is supported.  Please try with -no-kvm to see if 
it is a qemu or kvm issue, and also try the latest release to see you 
aren't encountering an already-fixed bug.

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

Re: Direct kernel boot without harddrive image

[Daire Byrne]

Avi,

----- "Avi Kivity" <avi@redhat.com> wrote:

> > Is direct kernel booting just not really supported properly or is it
> just to do with Qemu forgetting about the direct boot kernel/initrd
> after a reboot?
> 
> Direct kernel booting is supported.  Please try with -no-kvm to see if
> it is a qemu or kvm issue, and also try the latest release to see you
> aren't encountering an already-fixed bug.

I tried with -no-kvm and I get the same crash when I reboot the VM. I suppose it's a qemu bug then. I tried with the latest kvm-qemu (78) but perhaps I should try the latest Qemu and if it still breaks report the bug on the Qemu mailing list? It is like it forgets to boot the kernel and initrd again after a reboot and tries to boot from the harddrive instead.

Cheers,

Daire

Re: Direct kernel boot without harddrive image

[Daire Byrne]

----- "Daire Byrne" <Daire.Byrne@framestore.com> wrote:

> I tried with -no-kvm and I get the same crash when I reboot the VM. I
> suppose it's a qemu bug then. I tried with the latest kvm-qemu (78)
> but perhaps I should try the latest Qemu and if it still breaks report
> the bug on the Qemu mailing list? It is like it forgets to boot the
> kernel and initrd again after a reboot and tries to boot from the
> harddrive instead.

More weirdness with direct booting - using more than 2048MB causes the BIOS to repeatedly crash out. This only happens using "-kernel" and "-initrd".

Daire