Re: Disk geometry from /sys

[Francis Moreau]

Hi Seewer,

On Mon, Apr 14, 2008 at 2:57 PM, Seewer Philippe <philippe.seewer@xxxxxx> wrote:
>
>  As you've problably seen from the other answers, disk geometry is (except
> for a few older devices) unneeded inside the Linux kernel.

Yes but I'm doing userspace stuff and that's the reason I was asking for the
sysfs thing.

> I'd say thats the
> reason why there's no sysfs export and I'd further guess disk geometry is an
> artifact most would like to get rid of (or pushed into userspace).
>

Well, I looked at sfdisk(8) and parted(8) source code and they all need the
geometry description. If I understood correctly the reason why is that it
'prefers' to align partition sizes/starts on a cylinder boundary because some
bootloaders probably use CHS addressing, but I'm really not sure.

>  Anyway, if you really need it, try the patch below. Should apply cleanly to
> version 2.6.23.1 and gives you a geometry/ directory for each block device
> providing the getgeo function. It adds a setgeo counterpart for some
> subsystems as well, allowing 'echo something > ...' so please be careful.
>

Thanks but I probably won't use it. Using sfdisk, for example, is a
more portable
way to get the geometry from a script.

-- 
Francis
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