Mark Lord wrote:
Alan Cox wrote:
The fussy bit is that these commands require a non-standard
sector size, usually 520 bytes instead of 512.
Do we always know the worst case here as this breaks my pending patch to
use bounce buffers for PIO so we transfer with IRQ enabled and I need to
know the correct new worst case size.
Ugh. The drives default to 520 bytes (always),
The old IDE drives used to have 4 and 7 byte ECC (seen in ancient Phoenix
BIOS).
but can specify a different, preferred, length in
the IDENTIFY data. A SETFEATURES command is required
to change the setting from the default of 520.
You're wrong here (which is explainable by your patch bneing boken
protocol wise) -- there used to be two subcodes, one to selecyt vendor spcific
length (0x44), and one to selectt 4-byte ECC (0xBB). Not 8-byte!
In practice, I only ever use 520, because (1) it always works,
and (2) I'm only trying to corrupt drives, not write correct stuff. ;)
So we could modify the patch to limit it to a specific maximum,
or always require exactly 520 bytes without any hardship.
???
Certainly not the second. Vendor ECC length is indicated in the word 22
identify device info. Not sure how this gets translated to SCSI...
WBR, Sergei
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