From: Sudeep Holla <sudeep.holla@arm.com>
To: Robin Murphy <robin.murphy@arm.com>
Cc: Ayan Kumar Halder <ayankuma@amd.com>,
mark.rutland@arm.com, lpieralisi@kernel.org,
linux-arm-kernel@lists.infradead.org,
Sudeep Holla <sudeep.holla@arm.com>,
linux-kernel@vger.kernel.org,
Vladimir Murzin <vladimir.murzin@arm.com>,
Stefano Stabellini <sstabellini@kernel.org>
Subject: Re: SMP enablement on Cortex-R52 (using PSCI ?)
Date: Thu, 20 Apr 2023 10:51:22 +0100 [thread overview]
Message-ID: <20230420095122.chw527nozzwkopnx@bogus> (raw)
In-Reply-To: <ee7095b4-0bab-d98e-0f7e-633672458b50@arm.com>
On Wed, Apr 19, 2023 at 06:50:26PM +0100, Robin Murphy wrote:
> On 19/04/2023 9:47 am, Sudeep Holla wrote:
> >
> > I will check with the authors if EL3 is a must for PSCI implementation, but
> > IMO it must not be though every aspects described in the spec may not apply
> > when used across EL2/EL1 boundaries especially when EL3 is not implemented
> > in the hardware.
>
> Xen could provide PSCI to EL1 guests using the HVC conduit. However if EL2
> is the highest implemented EL, then Xen is the most privileged software in
> the system - it would have to own the EL2 exception vectors, and it would
> have to own the low-level CPU bringup code. At that point it just wouldn't
> make much sense to HVC *itself* via the PSCI protocol when it could simply
> call the function directly.
>
Agreed, I was focussing to much just on EL2/EL1. I don't know details on how
power management responsibilities are split between Dom0 and hypervisor, but
I am more interested in understanding how cpuidle/suspend would be structured
with the direct function calls.
--
Regards,
Sudeep
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prev parent reply other threads:[~2023-04-20 9:52 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-14 11:24 SMP enablement on Cortex-R52 (using PSCI ?) Ayan Kumar Halder
2023-04-18 12:14 ` Vladimir Murzin
2023-04-19 8:47 ` Sudeep Holla
2023-04-19 17:50 ` Robin Murphy
2023-04-20 9:51 ` Sudeep Holla [this message]
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