Messages in this thread |  | | Date | Fri, 28 Nov 2025 08:36:06 +0100 | | Subject | Re: [PATCH v1 0/2] powerpc/pseries/cmm: two smaller fixes | | From | "David Hildenbrand (Red Hat)" <> |
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On 11/28/25 06:05, Ritesh Harjani (IBM) wrote: > "David Hildenbrand (Red Hat)" <david@kernel.org> writes: > >> On 10/21/25 12:06, David Hildenbrand wrote: >>> Two smaller fixes identified while doing a bigger rework. >>> >>> Compile-tested only as I don't have an easy way to test right now. >>> >>> I would prefer for these patches to go through the MM tree as I will >>> be sending out a bigger version soon that is based on this series -- >>> I split of the fixes from the other stuff. >>> >> >> Ping, >> >> I tried to get CMM running again (using the simulation mode I introduced >> a while back), but so far my attempts to get a reasonable powernv VM >> booted in QEMU failed :( >> >> (e.g., Fedora qcow2 images use xfs, but the open powernv loader is based >> on a 5.10 kernel without some mystical XFS feature ...) >> >
Hi Ritesh,
> Sorry, I missed seeing this earlier. > > Do you have the link to simulation mode which you are referring above > please? So far I didn't find the support of this beyond Linux LPAR > (pseries), but maybe I missed it.
When I did a rework of the CMM balloon in 2019, I needed a way to test it. So I added
commit b1713975c31ae20ecc40fd00191ee3fa51445d4a Author: David Hildenbrand <david@kernel.org> Date: Thu Oct 31 15:29:31 2019 +0100
powerpc/pseries/cmm: Simulation mode
Let's allow to test the implementation without needing HW support. When "simulate=1" is specified when loading the module, we bypass all HW checks and HW calls. The sysfs file "simulate_loan_target_kb" can be used to simulate HW requests.
The simualtion mode can be activated using: modprobe cmm debug=1 simulate=1
And the requested loan target can be changed using: echo X > /sys/devices/system/cmm/cmm0/simulate_loan_target_kb
I allows for bypassing the absence of FW_FEATURE_CMO.
Back in the days I was able to test it with a pseries (or was it powernv?) machine we had here at RH. So far my attempts failed to test it in a similar fashion in QEMU.
-- Cheers
David
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