[ofa-general] Re: IPoIB-CM UC mode

[Or Gerlitz]

On 7/2/07, Michael S. Tsirkin <mst at dev.mellanox.co.il> wrote:
>
> > Quoting Or Gerlitz <ogerlitz at voltaire.com>:

> Is there any --other-- part of the stack (eg mthca,cm) that needs to be
> > enhanced for that?
>
> Not a whole lot.
> We need an API to detect this feature support in HW.  There could be a bit
> of
> work in mthca to detect HW/FW support for this feature, and enable
> connecting UC
> QPs to SRQ.  There could be a bit of debugging work in CM in case we hit
> some
> bugs with LAP messages (which I plan to use for liveness detection).
>

Thanks for the info. Can you please elaborate a little more on the LAP based
liveness detection mechanism you were thinking about? I might want to deploy
it in another app.

Actually, looking on IPoIB-CM RC based implementation I don't really
understand its "liveness detection" mechanism... In ipoib_cm_send_req() I
see that the code sets both the RC QP retries AND rnr retries to 0...
doesn't this mean that a single RNR NAK would cause a TX QP to move to
ERROR? can you clarify how do you use the "R" of "RC" here?

thanks,

Or.
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