[Qemu-devel] Possible bug?

[Qemu-devel] Possible bug?

[J.N. Herder]

Hi all,

I'm having some troubles with QEMU's hard disk images and may have bumped 
into a bug. I'm trying to import data into my emulated MINIX, but somehow 
it is truncated.

I successfully created a qemu-img called hda.img of 512 MB and installed 
the latest version from MINIX on it. Trying to import files by using the 
file as hdb image and reading from /dev/hdb in the emulated MINIX works 
perfectly fine for small files. For an import file above 1.5 MB the 
following weirdiness happens:

In linux:

$ qemu -hda hda.img -hdb import.tar.gz

After booting MINIX with QEMU:

# dd if=/dev/hdb of=import.tar.gz bs=1 count=1672014
# ls -l import.tar.gz
-rw-r--r-- 1 root operator 1548288 Jul 31 20:34 import.tar.gz

Somehow the file is truncated at exactly 1.5 MB, while the dd output 
indicates that all records were successfully read.
Inspection of /dev/hdb with MINIX' part tools also learns that the QEMU 
emulated hard disk is 1512 KB.

I'd like to note that for several small files (less than 1 MB) this 
procedure worked fine.

Another file of 75582464 bytes was truncated at 73584 KB.

Could this behaviour be caused by a bug in QEMU?

Please CC the reply to jnherder@cs.vu.nl as I'm not a list member.

Thanks,
Jorrit

Re: [Qemu-devel] Possible bug?

[Paul Brook]

On Monday 01 August 2005 18:27, J.N. Herder wrote:
> Hi all,
>
> I'm having some troubles with QEMU's hard disk images and may have bumped
> into a bug. I'm trying to import data into my emulated MINIX, but somehow
> it is truncated.
>
> I successfully created a qemu-img called hda.img of 512 MB and installed
> the latest version from MINIX on it. Trying to import files by using the
> file as hdb image and reading from /dev/hdb in the emulated MINIX works
> perfectly fine for small files. For an import file above 1.5 MB the
> following weirdiness happens:

The size of the image will be truncated to a whole number of cylinders. You 
should add padding so the image is a multiple of the cylinder size (depends 
on drive geometry, but usually 16*63*512 bytes)

Paul