Re: port-xen/57199: Pure PVH i386 guests hang on disk activity

[Taylor R Campbell <riastradh%NetBSD.org@localhost>]

The following reply was made to PR kern/57199; it has been noted by GNATS.

From: Taylor R Campbell <riastradh%NetBSD.org@localhost>
To: Brad Spencer <brad%anduin.eldar.org@localhost>
Cc: bouyer%antioche.eu.org@localhost, gnats-bugs%NetBSD.org@localhost,
	netbsd-bugs%NetBSD.org@localhost, gdt%lexort.com@localhost
Subject: Re: port-xen/57199: Pure PVH i386 guests hang on disk activity
Date: Mon, 15 Jul 2024 18:52:14 +0000

 > Date: Mon, 15 Jul 2024 14:31:41 -0400
 > From: Brad Spencer <brad%anduin.eldar.org@localhost>
 > 
 > b) I will test Taylor's patch on the DOMU.  Doing that on the DOM0 is
 > probably not something I can manage right now.
 
 I should clarify: I suspect this may be needed on the dom0, but only
 if the dom0 _also_ runs uniprocessor, i.e., single-vCPU.
 
 If you can run crash(8) or enter ddb on the dom0, you can check like
 so:
 
 # crash
 Crash version 10.0_STABLE, image version 10.0.
 WARNING: versions differ, you may not be able to examine this image.
 Kernel compiled without options LOCKDEBUG.
 Output from a running system is unreliable.
 crash> x/i membar_sync,3
 _membar_enter:  lock addq       $0,fffffffffffffff8 (%rsp)
 _membar_enter+0x7:      ret
 _membar_enter+0x8:      nopl
 
 If it says `lock addq' or `lock addl', you're good.  If it's just
 `addq' or `addl' with no `lock', the patch is needed.