booting kernel with kvm

[Paul Bolle]

On Wed, 2014-10-15 at 15:01 +0530, harisha ja wrote:
> I have windows 7 system and I have installed ubuntu using vmware. I
> have installed KVM on ubuntu and I am trying to boot the kernal image
> with KVM.

Does vmware emulate the KVM related chip functionality (ie, "VT" for an
x86 Intel CPU or "AMD-V (SVM)" for x86 AMD CPU)?

> But I am not sure what is the problem. I am stuck in this screen. Is
> something I am missing here? 
>
> The approach using kvm to put some logs and to see module
> initialization is wrong?. 
>
> The command I am using 
> kvm  -kernel ./arch/x86/boot/bzImage  -append root=/root/

You call this command in your vmware session of a virtual Ubuntu system,
don't you?

> I see the below message and then the qemu prompt does not boot and
> stops by displaying below traceback.
>
> Could not access KVM kernel module: No such file or directory
> failed to initialize KVM: No such file or directory

Is this the only message, or only the part you thought was interesting?

> QEMU 
> 5.1654731 Stack: 5.1654731 c18ea844 claea9a0 00000000 fffffffa
> d?861efc 00008001 d?8611 a35f91 5.1654731 cl8ddba8 d?861efc d7861efc
> fffffffa 00000000 d7b6e000 cl8dd6 ff3dc0 5.1654731 d7b6e000 6e6b6e75
> 2d6e??61 636f 6c62 2c30286b c1002930 d78611 13c248 5.1654731 
> Call Trace: 
> 5.1654731 l<c1a35f91>1 mount_block_root+Ox158/0x1de 
> 5.1654731 l<c1002930>1 ? do_general_protection+0x40/0x170 
> 5.1654731 l<c113c248>1 ? SyS_mknod+0x28/0x30 
> 5.1654731 l<cla3610a>1 mount_root+Oxf3/Oxfb 
> 5.1654731 l<c1a36235>1 prepare_namespace+0x123/0x167 
> 5.1654731 l<c112cf30>l ? SyS_access+0x20/0x30 
> 5.1654731 l<cla35cf7>1 kernel_init_freeable+Ox1b5/0x1c2 
> 5.1654731 l<c1a35545>1 ? do_early_param+0x74/0x74 
> 5.1654731 l<c174caab>1 kernel_init+Oxb/Oxe0
> 5.1654731 l<c175a041>1 ret_from_kernel_thread+0x21/0x30 
> 5.1654731 l<c174caa0>1 ? rest_init+0x60/0x60
> 5.1654731 Code: 00 00 00 00 31 ff 83 3d 8c a9 ae cl 00 74 05 e8 Oe dO
> 9 c? 44 24 04 a0 a9 ae cl c7 04 24 44 a8 Be cl e8 b6 05 00 00 fb 3116
> <35>1 15 83 75 f0 01 8b 45 f0 ff 15 80 a9 ae cl 01 c6 8d be 5.1654731
> EIP: l<c174f2e9>1 panic+0x165/0x197 SS:ESP 0068:d7861eb8 5.1654731 --I
> end trace a4Obaf277b417d8d 1-- 

This looks like the kind of backtrace one gets when the kernel can't
find its root device. I see something like it every now and then, and it
mostly means that I made a mistake when I configured a machine. It also
means, I think, that the KVM problem you quoted wasn't fatal for this
virtual boot.

Setting the root device might be tricky to get right when booting a
virtualized system. At least, I remember fiddling with it. But your
"root" kernel parameter should be something like:
    root=/dev/sda1

It rather depends on how your Ubuntu system is setup (ie, what the
layout is of the image that vmware uses to boot Ubuntu, apparently).


Paul Bolle