fine-grained PI control

[Anuj gupta]

On Fri, Jul 5, 2024 at 2:02 PM Christoph Hellwig <hch at lst.de> wrote:
>
> Hi all,
>
> Martin also mentioned he wanted to see the BIP_CTRL_NOCHECK,
> BIP_DISK_NOCHECK and BIP_IP_CHECKSUM checksum flags exposed.  Can you
> explain how you want them to fit into the API?  Especially as AFAIK
> they can't work generically, e.g. NVMe never has an IP checksum and
> SCSI controllers might not offer them either.  NVMe doesn't have a way
> to distinguish between disk and controller.
Yes, these flags are only valid in the context of SCSI. One possible
scheme can be that the API still has the ability to pass these flags
and the NVMe driver fails if the user specifies these flags.

>
> Last but not least the fact that all reads and writes on PI enabled
> devices by default check the guard (and reference if available for the
> PI type) tags leads to a lot of annoying warnings when the kernel or
> userspace does speculative reads.
In the current series the application can choose not to specify the
GUARD check flag, which would disable the guard checking even for PI
enabled devices. Did you still encounter errors or am I missing
something here?

--
Anuj Gupta