Re: libata transfer mode & FUA & mode sense page

[Jeff Garzik <jgarzik@pobox.com>]

Tejun Heo wrote:
> ATA FUA is interesting in that it's supported only for multisector PIO 
> and DMA protocols.  There is no ATA_CMD_PIO_WRITE_FUA_EXT.  So, when 

That's ok, that's 99% of all users anyway.

(pio-mult is merged in Albert's irq-pio branch)


> generating mode sense page, the status of FUA supported bit is dependent 
> on the configured transfer mode.

Yep.


> transfer mode configuration yet, I'm thinking of simply passing ap or 
> device down to mode sense functions and use it to report FUA status. How 
> does that sound?

That's fine.


> If dynamic transport configuration is implemented in the future (from EH 
> or explicit user input), this FUA bit will go on and off depending on 
> transfer mode.  Ugh... It seems that we'll need a way to raise UA for 
> configuration change and trigger revalidation of SCSI disk device.

Just one more thing to think about, before allowing userspace to change 
the transfer mode at will, during runtime :)

	Jeff