> Andries B. discovered that there is a jumper that allows one to select
> between 15/16 hardwired head reporting. They are shipped with the jumper
> selected to 15 and you loose about 5% capacity.
Worse yet, some laptops are shipped with 15-heads setting and
backup/re{format|partition}/restore is not too pleasant option.
> Since the geometry rules for disk translations larger than 8.4GB do not
> allow for 15 heads, he and I are discussing various options to account for
> the error that IBM did.
IIRC one the laptop where I've seen that lossage BIOS geometry was
munged to ???*240*63.
> The request is reasonable to add 15/16 combination, but the rule breaking
> leaves us wondering some. Since this is a geometry issue and Andries is
> primarily responsible for that part of the kernel, I will defer to his
> judgement.
> If you have a list of drive models and names they could be useful for
> determining the action needed to address the problem.
Hmm... Laptop in question wasn't mine, so I'll just Cc the owner. Oleg,
could you give the model name of that sucker/give additional details?
Linux managed to boot with the unpatched ide-disk.c and mounted everything
OK, but fdisk was very unhappy until I did s/15/16/ in the function in
question. After that geometry was recoginzed and fdisk returned into sane
state.
So there... I don't have additional datapoints. I think that reasonable
course of actions would be to recognize 240 heads as valid munge and check
for this 0x3fff*15*63 bogosity, maybe informing happy owner about the
situation. But then I'm VFS/filesystems hacker, and underlying stuff is
*not* an area I'm comfortable with ;-)
Cheers,
Al
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