Messages in this thread | | | Date | Sat, 14 Feb 2009 11:58:42 -0600 | From | Robert Hancock <> | Subject | Re: Very old IDE hard drive (240 MB) detected as 1.1 TB |
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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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