On 1/7/25 23:43, Robert Joslyn wrote:
-----Original Message-----
From: Shrikanth Hegde <sshegde@xxxxxxxxxxxxx>
Sent: Tuesday, January 7, 2025 5:10 AM
To: Robert Joslyn <robert_joslyn@xxxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx; linux-rt-users@xxxxxxxxxxxxxxx;
tglx@xxxxxxxxxxxxx; rostedt@xxxxxxxxxxx; Sebastian Andrzej Siewior
<bigeasy@xxxxxxxxxxxxx>
Subject: Re: [PATCH] powerpc: Allow scheduling of IRQ with PREEMPT_RT
[Caution - External]
On 1/7/25 17:26, Sebastian Andrzej Siewior wrote:
On 2024-12-26 11:12:38 [-0800], Robert Joslyn wrote:
This branch is needed to allow preemptible IRQs to be scheduled,
otherwise the kernel hangs during boot on my e300 based platforms.
This branch is needed for both CONFIG_PREEMPT and
CONFIG_PREEMPT_RT,
Hi Robert.
Are you running with preempt=full or enabled preempt_rt ?
rt is yet to be supported on powerpc. are you having it enabled out of tree?
I'm running PREEMPT_RT using the out of tree patches on 6.6.58-rt45:
https://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-stable-rt.git/
I haven't tried using the mainline kernel, since as you said, it doesn't have powerpc support for PREEMPT_RT yet.
Also, I have sent out patch to enable dynamic preemption. It uses
preempt_model_preemptible.
I think it should work for you as well. If you could give that a try and ensure it
works, it would be great.
https://urldefense.com/v3/__https://lore.kernel.org/all/20250106051919.5
5020-2-
sshegde@xxxxxxxxxxxxx/__;!!O7uE89YCNVw!IDeomstGeuiEZi9FmLHH8C2xo
PPo_ewL-
k2kiQ9CmVID35U4J_v3Dkafjo3RnS9ygPoUZWwyyp91SP2euRkKArk$
Does the dynamic preemption support let me enable the same functionality as PREEMPT_RT with the out of tree patches? I can test it out either way.
with preempt_rt, dynamic preemption allows you to switch between full
and lazy. without preempt_rt, you can switch between none,
voluntary,full and lazy.
Thanks,
Robert
