Re: Initial ahci(4) NCQ support on jdolecek-ncq branch, test/review wanted

["Jonathan A. Kollasch" <jakllsch%kollasch.net@localhost>]

On Thu, Apr 20, 2017 at 12:25:47AM +0200, Jaromír Doleček wrote:
> Hi,
> 
> I've committed the initial NCQ support, it's available at jdolecek-ncq
> branch (branch only over sys). It works under Parallels for now, and
> is ready for brave adventurers. There is sys/dev/ata/TODO.ncq which
> you might want to check, also.
> 
> If people want to try it out and give feedback, I'd really appreciate it.
> 
> I'll be busy for next 2-3 weeks elsewhere, so probably won't have too
> much time for bugfixing during the time. After that I plan to start
> testing with real hardware, and look on remaining bugs.
> 
> One of the more annoying bugs right now is that AHCI NCQ transfers
> pretty frequently timeout for me under Parallels. Maybe interrupt
> handling is not quite right yet in the driver. I only got so far to
> note that every transfer gets two interrupts, one with IS 0x8 and one
> 0x0 The 0x8 is Set device bit and is expected for NCQ, the other not
> so much.
> My understanding of ATA and AHCI specs is not good enough yet, so if
> somebody could look there and sanity check, I would be really glad.
> 
> Also, I've not modified mvsata(4) and siisata(4) drivers yet to enable
> NCQ. While the drivers seem to be mostly prepared, I lack the
> hardware, so have no way to test. I would really appreciate if folks
> with the hardware could check it out and possibly provide patches to
> enable the support there.

I plan to look at siisata(4).  I've got mvsata(4) hardware too.

> Last but not least, there is simply no consideration in AHCI for PMP
> in the changes. I have no idea if it needs special support. I hope
> not, but would be nice if our PMP experts would sanity check.
 
I've also got a port multiplier enclosure.  I suspect there may need to
be adjustments to the PMP paths.

Thanks for looking at this!  I'd been threatening to look at this for a
decade!

	Jonathan Kollasch