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SubjectRe: Very old IDE hard drive (240 MB) detected as 1.1 TB
Maciej W. Rozycki wrote:
> On Sat, 14 Feb 2009, Mark Lord wrote:
>
>>> It has the current capacity in words 57-58 swapped:
>>>
>>> /dev/sdb:
>>> 0c5a 037f 0000 000a 8723 0275 0037 0030
>>> 000a 0000 2020 2020 2020 2020 2020 424d
>>> 3948 4d31 5020 2020 0003 0040 0004 302e
>>> 3336 2020 2020 436f 6e6e 6572 2050 6572
>>> 6970 6865 7261 6c73 2032 3430 4d42 202d
>>> 2043 5033 3032 3534 2020 2020 2020 8010
>>> 0000 0001 0000 0200 0202 0001 037f 000a
>>> 0037 0007 82da 0000 0000 0000 0000 0000
>>>
>>>
>>> It must be 82da 0007, not 0007 82da.
>>> IIRC, the IDE core doesn't trust the value reported in these words
>> ..
>>
>> That's right. I wrote the IDE code that way
>> *specifically* due to a (different) Conner drive
>> I had here at the time.
>
> It happened for some Maxtor drives too. The reason is the ATA-1 spec was
> not explicit about how words 57 and 58 were meant to be ordered and some
> manufacturers interpreted it one and some the other way. It looks like
> libata needs to be fixed.

Here's the relevant code, it appears (drivers/ata/libata-core.c at line
1321):

static u64 ata_id_n_sectors(const u16 *id)
{
if (ata_id_has_lba(id)) {
if (ata_id_has_lba48(id))
return ata_id_u64(id, 100);
else
return ata_id_u32(id, 60);
} else {
if (ata_id_current_chs_valid(id))
return ata_id_u32(id, 57);
else
return id[1] * id[3] * id[6];
}
}

It looks like it's getting into the ata_id_current_chs_valid(id) path,
since all the values that function checks are indeed valid, but the
values in words 57-58 are not. There seems to be no real reason to use
those values since the same can be calculated from the reported CHS, so
you could change that code to:

if (ata_id_current_chs_valid(id))
return id[54] * id[55] * id[56];
else
return id[1] * id[3] * id[6];

Hanno, would you be able to try building a kernel with a modified
drivers/ata/libata-core.c as above (in current -git it would be changing
line 1330) and see if that resolves the problem?


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