[PATCH v3] iommu/arm-smmu-v3: Shrink command/event/PRI queues in kdump kernel

[Jason Gunthorpe]

On Tue, Aug 04, 2026 at 09:04:32AM -0700, Nicolin Chen wrote:
> On Tue, Aug 04, 2026 at 11:17:04AM -0300, Jason Gunthorpe wrote:
> > On Tue, Aug 04, 2026 at 03:02:46PM +0100, Will Deacon wrote:
> > > > Would skipping their allocation when is_kdump_kernel() be acceptable on
> > > > its own, or would you rather see it done differently?
> > > 
> > > With Nicolin's patch, we can just avoid allocating the priq and the evtq
> > > entirely in the kdump case. We can then add a cmdline option to control
> > > the maximum size of the cmdq, which is useful regardless of kdump.
> > 
> > I would still prefer kdump do this re-sizing automatically, even if we
> > do add a commandline. It makes it easire to deploy than having to know
> > secret command lines :\
> > 
> > So functionally I still think this patch is fine, though yes it points
> > out more things in Nicolin's work too.
> 
> I will send a v10 of mine, to skip the EVTQ/PRIQ allocations.

I think Robin's point is to structure the v10 so you introduce a bunch
of tunables, including something like 0 size to disable a feature.

Then have kdump default those tunables to the right thing

Jason