Re: kern/56857: ixg(4) doesn't work in legacy interrupt mode

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

The following reply was made to PR kern/56857; it has been noted by GNATS.

From: Manuel Bouyer <bouyer%antioche.eu.org@localhost>
To: gnats-bugs%netbsd.org@localhost
Cc: kern-bug-people%netbsd.org@localhost, gnats-admin%netbsd.org@localhost, netbsd-bugs%netbsd.org@localhost
Subject: Re: kern/56857: ixg(4) doesn't work in legacy interrupt mode
Date: Sat, 28 May 2022 18:58:48 +0200

 On Thu, May 26, 2022 at 11:35:01AM +0000, bouyer%antioche.eu.org@localhost wrote:
 >  [...]
 > 
 > 	cause igx(4) device to fail to receive packet (or to receive them
 > 	with very high latency). Other devices, including nvme(4) and wm(4)
 > 	works fine in legacy mode. This is a show stopper for Xen (see PR
 > 	kern/55667).
 > 	The device works fine with MSI-X. I coulnd't test with MSI as
 > 	disabling only MSI-X cause the kernel to panic (probably unrelated to
 > 	igx(4)), but experiments with Xen suggest that it fails too.
 
 Restricting the Xen dom0 to a single CPU makes ixg work with MSI.
 So maybe the issue is that too much queues are allocated when one interrupt
 per queue is not available ?
 
 -- 
 Manuel Bouyer <bouyer%antioche.eu.org@localhost>
      NetBSD: 26 ans d'experience feront toujours la difference
 --