On 11/28/25 08:49, Ritesh Harjani (IBM) wrote:
"David Hildenbrand (Red Hat)" <[email protected]> writes:
On 11/28/25 06:05, Ritesh Harjani (IBM) wrote:
"David Hildenbrand (Red Hat)" <[email protected]> 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 <[email protected]>
Date: Thu Oct 31 15:29:31 2019 +0100
powerpc/pseries/cmm: Simulation mode
aah right. I should have looked closely. I was thinking you meant
somewhere in Qemu, so I was only looking there.
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.
Right. Let me give it a try first with pseries Qemu. Otherwise I have an
access to pseries LPAR too. I can verify it there.
Ah, now I realize my problem: I tried with Fedora 43 in a powerpc VM but
the modprobe didn't do anything.
Looking again:
# grep CONFIG_CMM /boot/config-6.17.1-300.fc43.ppc64le
CONFIG_CMM=y
So modprob'ing won't do as the module is built in.
Anyhow, compiling a kernel inside a QEMU VM might take a while, so if
you can beat me to it I wouldn't be mad :)
Re powernv vs. powerpc: yeah, it's confusing. For some reason I thought
I tested it in the days on powernv. Maybe that's simply because I was
only able to get my hands on such a machine. Looking again, it should
indeed be able to be simulated on a simple powerpc VM.
--
Cheers
David
