[PATCH v2] nvme: reserve a keep-alive admin tag for all transports

[Christoph Hellwig]

On Fri, May 15, 2026 at 03:12:48AM -0400, Chao Shi wrote:
> A quirk-based approach was considered but no PCIe controller
> documented to declare KAS != 0 was found (two enterprise SSDs tested
> locally report KAS=0), so an allowlist has no entries today.

Quirking for spec allowed behavior sounds odd.  If we care about
testing KA for PCIe it should be trivial to implement in nvmet-epf
in the kernel, but I'm not sure there is much of a point in that.

> Reproducer (run as root on an unpatched kernel with a PCIe NVMe device):

Can you wire this up as a testcase in blktests?

The patch itself looks good:

Reviewed-by: Christoph Hellwig <hch at lst.de>