Re: LibPATA code issues / 2.6.15.4

From: Tejun Heo
Date: Mon Feb 27 2006 - 20:30:46 EST


Hello, Mark.

Mark Lord wrote:

.. hold off on 2.6.16 because of this or not?


It certainly is dangerous. I guess we should turn off FUA for the time being. Barrier auto-fallback was once implemented but it didn't seem like a good idea as it was too complex and hides low level bug from higher level. The concensus seems to be developing blacklist of drives which lie about FUA support (currently only one drive). Official kernel doesn't seem to be the correct place to grow the blacklist, Maybe we should do it from -mm?


Well, no doubt whatsoever about it being a "regression",
since the FUA code is *new* in 2.6.16 (not present in 2.6.15).

The FUA code should either get fixed, or removed from 2.6.16.


Actually, now that I've done a little more digging, this FUA stuff
is inherently dangerous as implemented. A least a few SATA controllers
including pipelines and whatnot that rely upon recognizing the (S)ATA
opcodes being using. And I sincerely doubt that any of those will
recognize the very newish (and aptly named..) FUA opcodes.

These may be unsafe in general, unless we tag controllers as
FUA-capable and NON-FUA-capable, in addition to tagging the drives.

All sii controllers and piix/ahci seem to handle FUA pretty ok. And yeah, we may have to create controller blacklist too.

BTW, can you let me know what drive we're talking about now (model name and firmware revision)?

--
tejun
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