On Friday 11 July 2008 22:14:09 Alan Cox wrote:
> > > commenting out the error check after ata_dev_init_params() call in
> > > ata_dev_read_id() function (libata-core.c), I got at least the device
> > > name. The capacity is 0 so it doesn't work, obviously:
>
> If you don't read the ID then it wouldn't.
>
> > I captured the IDENTIFY data from the virtual device. I'm not ATA guru
> > but looking at the data, there are zeros at many places where something
> > should be. That number starting at 0x78 looks like size of the array in
> > sectors (0x4C726C or 0x4C6C72 - the array is built from 2.5GB and 6.4GB
> > drives).
>
> The Ident data for the virtual device is fairly sparse but the specs
> don't require a lot of the field are filled in and only the LBA really
> matters.
The problem is that ata_id_n_sectors() function:
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];
}
}
fails to retrieve the LBA48 value.
This is because the ata_id_has_lba() test
#define ata_id_has_lba(id) ((id)[49] & (1 << 9))
fails as the identify data contains only zeros at word 49 (byte 0x62).
Another problem is that ata_id_has_lba48() would fail too - that will break
array over 2TB (if the controller BIOS and firmware can do it).
Looks like this needs to force LBA48 with these virtual drives.
--
Ondrej Zary
--
To unsubscribe from this list: send the line "unsubscribe linux-ide" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
