[openib-general] the max_send/recv_sge value in the QP creation init attribute can't accept max s/g value in memfree devices for UD QPs

[Dotan Barak]

in memfree Mellanox HCAs (for example: 25204) there is a problem with the s/g size in the mthca driver

the reported value (from the query HCA verb in user level) is 30.

when i try to create an RC QP with 30 s/g entries it fails (with 29 s/g the QP can be created)
when i try to create an UD QP with 28 s/g entries it fails (with 27 s/g the QP can be created)

there are 2 issues:
1) the query HCA report a higher value of s/g entries than the HCA can support
2) which value should be reported by the query HCA as the maximum supported value of s/g entries in a QP?
	29:  which is supported only by RC/UC QPs
		or
	28: which is supported by all transport types (but decrease the number of s/g entries that an RC QP can support)

what do you think?

Dotan Barak
Software Verification Engineer
Mellanox Technologies LTD
Tel: +972-4-9097200 Ext: 231 Fax: +972-4-9593245
P.O. Box 86 Yokneam 20692 ISRAEL.
Home: +972-77-8841095  Cell: 052-4222383

[ May the fork be with you ]

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