Re: Is there any plan to support CXL GPF in Linux

[Christoph Hellwig <hch@infradead.org>]

On Mon, Jul 08, 2024 at 05:42:39PM -0700, Dan Williams wrote:
> One thing that guide does not cover is what should OS software do with a
> dirty shutdown failure. To my knowledge there is no specific plumbing
> for handling NVME device write-cache failures beyond: "hope filesystem
> logging and metadata checksums can recover a consistent filesystem".
> 
> I do agree that the driver has a responsibility to set switch timeout
> values, but that is more an unfortunate complexity imposed by the spec.
> Just set the max and rely on devices to minimize GPF response times to
> avoid the worst case wait times that those timeouts imply. In any event,
> enabling that is "up for grabs."

Why would anyone specifically care about a (presumably non-volatile) write
cache failure?  A non-volatile write cache is simply part of the device
and it's failure rate guarantee.  So any data lost from it will be
recovered the same way as a media failure, SOC failure, interconnect
failure, etc.