Re: [Qemu-devel] [PATCH 04/32] vvfat: Do not clobber the user's geometry

[Kevin Wolf <kwolf@redhat.com>]

Am 04.07.2012 18:25, schrieb Paolo Bonzini:
> Il 04/07/2012 17:23, Kevin Wolf ha scritto:
>>>>     opts        LCHS        def. PCHS
>>>>        :floppy:   80, 2,36  5,16,63
>>>>     :32:floppy:   80, 2,36  5,16,63
>>>>     :16:floppy:   80, 2,36  5,16,63
>>>>     :12:floppy:   80, 2,18  2,16,63
>>>>
>>>> Silly thing to do for use with a hard disk.
>>>>
>>>> However, the "raw" format can be suppressed by adding an
>>>> redundant-looking "format=vvfat" to "file=fat:FOO".  Then, vvfat's
>>>> hint clobbers the user's geometry, i.e. -drive options cyls, heads,
>>>> secs get silently ignored.  Don't do that.
>>>>
>>>> No change without format=vvfat.  With it, the user's hard disk
>>>> geometry (-drive options cyls, heads, secs) is now obeyed, and the
>>>> default hard disk geometry with :floppy: now matches the one without
>>>> format=vvfat.
>>>>
>>>> Signed-off-by: Markus Armbruster <armbru@redhat.com>
>> For some values of "obeyed". If I understand correctly, the user defined
>> geometry will indeed by visible for the device emulation now, but this
>> still doesn't mean that vvfat also provides an image that matches this
>> geometry. Not sure if it is a good idea to allow such mismatches.
>>
> 
> Does this only matter if you declare an image with :floppy: and pass it
> as a hard disk?  Then we can honestly say we don't care...

As I understand it, the patch has two effect:

1. the user's hard disk geometry (-drive options cyls, heads, secs) is
now obeyed
2. the default hard disk geometry with :floppy: now matches the one
without format=vvfat

I don't care about 2. indeed, but doing 1. right would be nice.

Kevin