nvme: Export constants for min and max queue sizes
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Authored by jhb on Mar 20 2024, 11:23 PM.

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imp
chuck

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rG1931b75e004f: nvme: Export constants for min and max queue sizes

Summary

These are useful for NVMe over Fabrics.

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rG FreeBSD src repository

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jhb created this revision.Mar 20 2024, 11:23 PM

Herald added a subscriber: dab. · View Herald TranscriptMar 20 2024, 11:23 PM

jhb requested review of this revision.Mar 20 2024, 11:23 PM

jhb added a child revision: D44442: nvme: Add SGL structure and constants for use in NVMe commands.

Harbormaster completed remote builds in B56712: Diff 136000.Mar 20 2024, 11:23 PM

imp added inline comments.Mar 21 2024, 9:34 AM

sys/dev/nvme/nvme.h
71	Where does this number come from?

jhb added inline comments.Mar 21 2024, 5:00 PM

sys/dev/nvme/nvme.h

See 4.1.3 in the base NVMe spec 1.4b.

4.1.3 Queue Size

The Queue Size is indicated in a 16-bit 0’s based field that indicates the number of slots in the queue. The minimum size for a queue is two slots. The maximum size for either an I/O Submission Queue or an I/O Completion Queue is defined as 64 Ki slots, limited by the maximum queue size supported by the controller that is reported in the CAP.MQES field. The maximum size for the Admin Submission and Admin Completion Queue is defined as 4 Ki slots. One slot in each queue is not available for use due to Head and Tail entry pointer definition.

That is the source for all 4 of these numbers.

This revision was not accepted when it landed; it landed in state Needs Review.Mar 23 2024, 12:26 AM

Closed by commit rG1931b75e004f: nvme: Export constants for min and max queue sizes (authored by jhb). · Explain Why

This revision was automatically updated to reflect the committed changes.

jhb added a commit: rG1931b75e004f: nvme: Export constants for min and max queue sizes.