Re: Re: [Qemu-devel] kqemu 0.6.2 and XP

[Andreas Bollhalder]

I tried the math on my WinXP host with Win2k guest.

When using the following math with my 8192MB QCOW image, QEMU refuse
to start:

1 Block = 512 Bytes

Cylinders = Blocks / (Heads * Sectors)

(kBytes * 2) / (16 * 63)
(8388608 kBytes * 2) / (16 * 63)

For 8192MB Image: -hdachs 16644,16,63


I brute forced the cylinder value, QEMU will start with a lower or
equal value of 16383 cylinders.

I made my own math based on this:

Cylinders = Blocks / (Heads * (Sectors + 1)) - 1

(kBytes * 2) / (16 * 64) - 1
(8388608 kBytes * 2) / (16 * 64) - 1

For 8192MB Image: -hdachs 16383,16,63


I'm realy confused about what's right or not. I created the image with
the QEMU Manager. Can anyone explain this ???

Andreas


Ben Taylor wrote:

> I forgot one very important part.  The calculation needs
> to be <img size in bytes> / (heads * sectors per cylinder 
> * 512 bytes) = cylinders. so in your case, the calculation is close

> well, the default sector size is 512, and you've done
> your sizing in number of 1k blocks, your calculations was
> close.  It should be:
>
>   blocks     secs/block      hds     sec/cyl
>
> (2 000 000   *   2 )    /  (   16   *   63 ) = 3968

> The first time I did the math, my 2g partition went
> to 8g partition when I used the -hdachs parameters
> cause I really screwed up the math.  (it appears if
> you mess your c-h-s values, your image since may
> change. :-)

> HTH, and sorry for the confusion.

> Ben