Phillip Susi wrote:
> Seewer Philippe wrote:
>
>> Hello all!
>>
>> I don't want to start another geometry war, but with the introduction of
>> the general getgeo function by Christoph Hellwig for all disks this
>> simply would become a matter of extending the basic gendisk block driver.
>>
>> There are people out there (like me) who need to know about disk
>> geometry. But since this is clearly post 2.6.16 I prefer to ask here
>> before writing a patch...
>>
>
>
> Why do you need to know about geometry? Geometry is a useless fiction
> that only still exists in PC system BIOS for the sake of backward
> compatibility with software that was originally designed to operate with
> MFM and RLL disks that actually used geometric addressing. These days
> there is no such thing; it's just made up by the bios.
...Thats why I said i didn't want to start another geometry war. But
then again, I did write RFC too, yes?
Yes, geometry is a fiction. And a bad one at that. To be honest I'd
rather get rid of it completely. But you said it: The geometry still
exists for the sake of backward compatibility. If it is still there, why
not export it? That's what sysfs is for...
Additionally have a look at libata-scsi.c which is part of the SATA
implementation. Theres CHS code in there...
Personally I want the geometry information in sysfs because debugging
partition tables not written by linux tools becomes just that tad more
easier...
>
>> Q1: Yes or No?
>> If no, the other questions do not apply
>>
>> Q2: Where under sysfs?
>> Either do /sys/block/hdx/heads, /sys/block/hdx/sectors, etc. or should
>> there be a new sub-object like /sys/block/hdx/geometry/heads?
>>
>
>
> This is not suitable because block devices may not be bios accessible,
> and thus, nowhere to get any bogus geometry information from. Even if
> it is, do we really want to be calling the bios to get this information
> and keep it around?
I did not say I'd implement it for _all_ devices. In fact I indent to
make geometry available only for devices whose drivers provide the
getgeo function.
>
>> Q3: Writable?
>> Under some (weird) circumstances it would actually be quite nice to
>> overwrite the kernels idea of a disks geometry. This would require a
>> general function like setgeo. Acceptable?
>>
>>
>
>
> What for? The only purpose to geometry is bios compatibility. Changing
> the kernel's copy of the values won't do any good because the bios won't
> be changed.
Exactly. I don't want the kernel to fix BIOS problems. But i want to
give userland the opportunity to overwrite what the kernel thinks (as in
/proc/ide/hdx/settings).
One example where this might be usable is connecting a PATA drive using
an Adapter to SATA. PATA returns the drive's geometry. SATA defaults to
x/255/63...
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
