Re: [Xen-devel] Why cannot HVM open a file as a floopy disk?

[Akio Takebe <takebe_akio@xxxxxxxxxxxxxx>]

>Akio Takebe writes ("Re: [Xen-devel] Why cannot HVM open a file as a floopy 
>disk?"):
>> Thank you very much for your elaborating.
>> We usually use /dev/floppy of dom0 as floppy disk of guest.
>
>Right, and the code specifically checks whether the backing object in
>dom0 is a block device, and if so treats it unconditionally as raw.
>
>> So a raw format floppy disk is not important.
>
>I'm not sure what you're saying ?  I asked:
>  Does anyone use Xen with non-raw floppy disk images in disk files ?
I thought /dev/floppy is treated as bdrv_host_device
rather than bdrv_raw.
Does raw format mean both bdrv_host_device and bdrv_raw?

>
>> The restriction is reasonable, but xend would need to be fixed
>> because it hangup.
>
>The error handling is appallingly bad, I'm afraid.
>
>> Also I concern about a emulate ide disk of the raw format.
>> Is it also vulnerable?
>
>No, there are no vulnerabilities of this kind in our tree - precisely
>because of the refusal of the format-guessing algorithm to return
>`raw', which is a change I introduced.  The effect is that any attempt
>to provide a raw image, in circumstances where the code attempts to
>guess the format, fails.
>
>In upstream qemu the default configuration is vulnerable, I think, for
>most block devices, but I haven't double-checked the latest code.  On
>the other hand in general in recent upstream qemu it is always
>possible to specify the format, elminating the problem.
Thank you, I understand.

Best Regards,

Akio Takebe


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