[Qemu-devel] qemu-img documentation

[Qemu-devel] qemu-img documentation

[Fabrice Bellard]

Hi,

I added some documentation about qemu-img (it is updated on the web site 
too). You should read it. Packagers should use the CVS to include the 
qemu-img man page before the 0.6.2 release is out.

Fabrice.

Re: [Qemu-devel] qemu-img documentation

[Hetz Ben Hamo]

Thats the problem, Fabrice..

I tried a fresh new virtual disks and new installation, and the
problem occured. Not old virtual disks (pre 0.6.x)..

Thanks,
Hetz

On Mon, 15 Nov 2004 23:58:13 +0100, Fabrice Bellard <fabrice@bellard.org> wrote:
> Hi,
> 
> I added some documentation about qemu-img (it is updated on the web site
> too). You should read it. Packagers should use the CVS to include the
> qemu-img man page before the 0.6.2 release is out.
> 
> Fabrice.
> 
> _______________________________________________
> Qemu-devel mailing list
> Qemu-devel@nongnu.org
> http://lists.nongnu.org/mailman/listinfo/qemu-devel
>

Re: [Qemu-devel] qemu-img documentation

[Fabrice Bellard]

Hetz Ben Hamo wrote:
> Thats the problem, Fabrice..
> 
> I tried a fresh new virtual disks and new installation, and the
> problem occured. Not old virtual disks (pre 0.6.x)..

Try my last fix. The important fix is in hw/ide.c:ide_guess_geometry(). 
I think the problem is that after reboot when installing 
ide_guess_geometry() returns an invalid geometry because the BIOS 
translated geometry is stored in the MBR instead of the real hard disk 
geometry.

For the desperate user, I added an option to manually specify the BIOS 
translation mode.

Fabrice.

Re: [Qemu-devel] qemu-img documentation

[ML]

---
Fabrice Bellard said the following on 11/16/2004 02:46 AM:

> Try my last fix. The important fix is in hw/ide.c:ide_guess_geometry(). 
> I think the problem is that after reboot when installing 
> ide_guess_geometry() returns an invalid geometry because the BIOS 
> translated geometry is stored in the MBR instead of the real hard disk 
> geometry.
> 
> For the desperate user, I added an option to manually specify the BIOS 
> translation mode.

With this fix now I can boot XP images newly created with 0.6.1 but I can't 
boot any longer my older images created with versions < 0.6.1 unless I specify 
hda geometry on the command line.
Not a big deal though, I can run QEMU happily with that :)

Thanks for the great work, Fabrice!

Ciao,
Piero

Re: [Qemu-devel] qemu-img documentation

[Jason Brittain]

ML wrote:
> ---
> Fabrice Bellard said the following on 11/16/2004 02:46 AM:
> 
>> Try my last fix. The important fix is in 
>> hw/ide.c:ide_guess_geometry(). I think the problem is that after 
>> reboot when installing ide_guess_geometry() returns an invalid 
>> geometry because the BIOS translated geometry is stored in the MBR 
>> instead of the real hard disk geometry.
>>
>> For the desperate user, I added an option to manually specify the BIOS 
>> translation mode.
> 
> With this fix now I can boot XP images newly created with 0.6.1 but I 
> can't boot any longer my older images created with versions < 0.6.1 
> unless I specify hda geometry on the command line.

This is going to cause lots of people to not be able to figure out
how to use qemu anymore after an upgrade.  For example, even if I
knew that I needed to use the -hdachs option (pronounced "headaches"),
how would I know what geometry numbers to give it?  I'm not real
good with this sort of thing, and I haven't found any docs yet that
try to explain it from the perspective of a VM user.  I know, I know,
you can't have everything.  But, I do think this will cause users
repeated hdachs.  :)

-- 
Jason Brittain

Re: [Qemu-devel] qemu-img documentation

[Panagiotis Issaris]

Hi,

Jason Brittain wrote:

> ML wrote:
>
>> ---
>> Fabrice Bellard said the following on 11/16/2004 02:46 AM:
>>
>>> Try my last fix. The important fix is in 
>>> hw/ide.c:ide_guess_geometry(). I think the problem is that after 
>>> reboot when installing ide_guess_geometry() returns an invalid 
>>> geometry because the BIOS translated geometry is stored in the MBR 
>>> instead of the real hard disk geometry.
>>>
>>> For the desperate user, I added an option to manually specify the 
>>> BIOS translation mode.
>>
>>
>> With this fix now I can boot XP images newly created with 0.6.1 but I 
>> can't boot any longer my older images created with versions < 0.6.1 
>> unless I specify hda geometry on the command line.
>
>
> This is going to cause lots of people to not be able to figure out
> how to use qemu anymore after an upgrade.  For example, even if I
> knew that I needed to use the -hdachs option (pronounced "headaches"),
> how would I know what geometry numbers to give it?  I'm not real
> good with this sort of thing, and I haven't found any docs yet that
> try to explain it from the perspective of a VM user.  I know, I know,
> you can't have everything.  But, I do think this will cause users
> repeated hdachs.  :)
>
I've used "fdisk c.img" and used the reported values as parameters
for hdachs. This together with specifying the bios translating mode
enabled me to boot old qemu images again.

So, I used:
"fdisk c.img"

Used the p command to print the partition table, which also
shows the necessary disk information:
16 heads, 63 sectors/track, 4161cylinders

And started qemu:
"qemu -hda c.img -hdachs 4161,16,63,none"

Worked for me, but I don't know if fdisk is always
right.

With friendly regards,
Takis

-- 
------------------------------------------------------------------------
Panagiotis Issaris
Katholieke Universiteit Leuven
Division Production Engineering,
Machine Design and Automation
Celestijnenlaan 300B              panagiotis.issaris@mech.kuleuven.ac.be
B-3001 Leuven Belgium                 http://www.mech.kuleuven.ac.be/pma
------------------------------------------------------------------------

Re: [Qemu-devel] qemu-img documentation

[Johannes Schindelin]

Hi,

On Tue, 16 Nov 2004, Panagiotis Issaris wrote:

> So, I used:
> "fdisk c.img"
>
> Used the p command to print the partition table, which also
> shows the necessary disk information:
> 16 heads, 63 sectors/track, 4161cylinders
>
> And started qemu:
> "qemu -hda c.img -hdachs 4161,16,63,none"

IMHO this should definitely go into the documentation.

Ciao,
Dscho

Re: [Qemu-devel] qemu-img documentation

[ML]

---
Panagiotis Issaris said the following on 11/16/2004 04:42 PM:

> I've used "fdisk c.img" and used the reported values as parameters
> for hdachs. This together with specifying the bios translating mode
> enabled me to boot old qemu images again.
> 
> So, I used:
> "fdisk c.img"
> 
> Used the p command to print the partition table, which also
> shows the necessary disk information:
> 16 heads, 63 sectors/track, 4161cylinders
> 
> And started qemu:
> "qemu -hda c.img -hdachs 4161,16,63,none"
> 
> Worked for me, but I don't know if fdisk is always
> right.

On my newer XP disk images, fdisk seems to report correctly the number of heads 
and sectors but fails to get the number of cylinders and complains with a "you 
must set cylinders" message.
On my older images, it doesn't seem to be able to guess anything.
Hdparm -g exits with a "Value too large for defined data type" message in both 
cases.

Ciao,
Piero

Re: [Qemu-devel] qemu-img documentation

[Jim C. Brown]

On Wed, Nov 17, 2004 at 09:09:49AM +0100, ML wrote:
> Hdparm -g exits with a "Value too large for defined data type" message in 
> both cases.
> 

This is a known problem with 32-bit linux programs in general ... to handle
files larger than 2GB, the linux program must use fseeko(), ftello(), etc
and then it must have been compiled with large file support. This problem
doesn't exist on 64-bit archs where fseek(), ftell(), etc return 64bit
integers.

I have never used hdparm so I can't give any more info on it (tho I would
expect that hdparm should have no problem with >2GB files as most actual hard
disks are larger than this) but I have seen this problem with grep and file
(my versions are quite old).

-- 
Infinite complexity begets infinite beauty.
Infinite precision begets infinite perfection.

Re: [Qemu-devel] qemu-img documentation

[Fabrice Bellard]

Jason Brittain wrote:
> ML wrote:
> 
>> ---
>> Fabrice Bellard said the following on 11/16/2004 02:46 AM:
>>
>>> Try my last fix. The important fix is in 
>>> hw/ide.c:ide_guess_geometry(). I think the problem is that after 
>>> reboot when installing ide_guess_geometry() returns an invalid 
>>> geometry because the BIOS translated geometry is stored in the MBR 
>>> instead of the real hard disk geometry.
>>>
>>> For the desperate user, I added an option to manually specify the 
>>> BIOS translation mode.
>>
>>
>> With this fix now I can boot XP images newly created with 0.6.1 but I 
>> can't boot any longer my older images created with versions < 0.6.1 
>> unless I specify hda geometry on the command line.
> 
> 
> This is going to cause lots of people to not be able to figure out
> how to use qemu anymore after an upgrade.  For example, even if I
> knew that I needed to use the -hdachs option (pronounced "headaches"),
> how would I know what geometry numbers to give it?  I'm not real
> good with this sort of thing, and I haven't found any docs yet that
> try to explain it from the perspective of a VM user.  I know, I know,
> you can't have everything.  But, I do think this will cause users
> repeated hdachs.  :)

I can do the following:

- The default translation will be 'none', so that older images will be 
usable without problems (but not the ones created recently).

- there will be a separate option '-hdatranslation' to change the 
default translation to use 0.6.1 images and to use old OSes such as NT 4.0.

Fabrice.