linux-kernel - Re: [PATCH 00/33] arm_mpam: Add basic mpam driver

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Message-ID: <aR4j/pbRLQYdeA+K@x1>
Date: Wed, 19 Nov 2025 12:09:34 -0800
From: Drew Fustini <fustini@...nel.org>
To: Jonathan Cameron <jonathan.cameron@...wei.com>
Cc: Ben Horgan <ben.horgan@....com>, james.morse@....com,
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Subject: Re: [PATCH 00/33] arm_mpam: Add basic mpam driver

On Wed, Nov 19, 2025 at 10:00:51AM +0000, Jonathan Cameron wrote:
> On Tue, 18 Nov 2025 14:55:07 -0800
> Drew Fustini <fustini@...nel.org> wrote:
> 
> > On Tue, Nov 18, 2025 at 02:11:31PM +0000, Ben Horgan wrote:
> > > Hi Drew,
> > > 
> > > On 11/16/25 17:16, Drew Fustini wrote:  
> > > > On Fri, Nov 07, 2025 at 12:34:17PM +0000, Ben Horgan wrote:  
> > > >> Hi all,  
> > > > [snip]  
> > > >> The rest of the driver can be found here: (no updated version - based on v3)
> > > >> https://git.kernel.org/pub/scm/linux/kernel/git/morse/linux.git mpam/snapshot/v6.18-rc1  
> > > > 
> > > > Does anyone know of a hosting platform that offers ARM machines that
> > > > have MPAM?  
> > > 
> > > As far as I know there aren't any.
> > > 
> > > There is some MPAM support in the Orion Radxa board which is likely the
> > > cheapest option. The MPAM acpi table isn't in the firmware though so
> > > you'd need to load a custom table. James has this working.  
> > 
> > Thank you, I didn't realize that there was a dev board that supports
> > MPAM. I didn't want to the expense or noise of a rackable server :)
> > 
> > Drew
> > 
> Hi Drew,
> 
> Obvious not functional as such, but I did spin qemu emulation with a bunch
> of introspection so you could see what was configured.  Aim was to poke
> corner cases more easily than with real hardware. Did it's job at the time
> and shook out some bugs.
> 
> I haven't rebased it recently though.
> https://lore.kernel.org/qemu-devel/20230808115713.2613-1-Jonathan.Cameron@huawei.com/
> 
> https://gitlab.com/jic23/qemu/-/commits/mpam-2023-sept-01
> Has what looks to be a slightly more recent rebase.
> 
> No monitor support though.
> 
> I might bring this back to poke the rest of this series as it moves forwards
> (or if anyone else wants to they are welcome to do so)
> 
> FWIW we could in theory hook this up to the cache plugins to get some 'plausible'
> numbers, but I never bothered as we have hardware (as seen by tested-by's on this
> series).
> 
> Jonathan

Thanks for pointing out your series and the branch from James. Qemu is
the cheapest way for me to try MPAM :)

Drew