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From: Marc Zyngier <maz@kernel.org>
To: Mark Brown <broonie@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org,
	Will Deacon <will@kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Ard Biesheuvel <ardb@kernel.org>,
	danielmentz@google.com, saravanak@google.com,
	kernel-team@android.com
Subject: Re: [PATCH 0/6] arm64: Disabling SVE/SME from the command-line
Date: Mon, 27 Jun 2022 16:30:36 +0100	[thread overview]
Message-ID: <878rpi2kf7.wl-maz@kernel.org> (raw)
In-Reply-To: <YrnKTCunW97kPP8s@sirena.org.uk>

On Mon, 27 Jun 2022 16:18:36 +0100,
Mark Brown <broonie@kernel.org> wrote:
> 
> On Mon, Jun 27, 2022 at 04:14:06PM +0100, Marc Zyngier wrote:
> 
> > The main victim here is SVE, because it seems that people have all
> > sort of broken firmware out there, and that a distribution kernel
> > cannot boot on that. And since we have a dependency between SVE and
> > SME, disabling the former also disables the latter.
> 
> Oh dear, I've not seen any reports of this.  I'm guessing it's TF-A just
> not enabling the requisite traps, coupled with people using prebuilt
> kernels that turned off SVE when doing validation?

Most probably something along these lines. The case I'm aware of
involves booting a vanilla kernel on a system with a half baked
firmware. I have little sympathy for these systems, but this looks
like a reasonable ask to be able to disable a feature from the command
line in order to pinpoint the issue.

Will someone ship a system with this baked into the command line? I
don't believe it for a second (/me ducks).

	M.

-- 
Without deviation from the norm, progress is not possible.

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  reply	other threads:[~2022-06-27 15:31 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-06-27 15:14 [PATCH 0/6] arm64: Disabling SVE/SME from the command-line Marc Zyngier
2022-06-27 15:14 ` [PATCH 1/6] arm64: Rename the VHE switch to "finalise_el2" Marc Zyngier
2022-06-27 15:14 ` [PATCH 2/6] arm64: Save state of HCR_EL2.E2H before switch to EL1 Marc Zyngier
2022-06-27 15:14 ` [PATCH 3/6] arm64: Allow sticky E2H when entering EL1 Marc Zyngier
2022-06-27 15:14 ` [PATCH 4/6] arm64: Factor out checking of a feature against the override into a macro Marc Zyngier
2022-06-28 11:28   ` Mark Brown
2022-06-29 15:46     ` Marc Zyngier
2022-06-29 16:00       ` Mark Brown
2022-06-27 15:14 ` [PATCH 5/6] arm64: Add the arm64.nosme command line option Marc Zyngier
2022-06-27 17:04   ` Mark Brown
2022-06-27 18:08     ` Marc Zyngier
2022-06-27 18:20       ` Mark Brown
2022-06-27 15:14 ` [PATCH 6/6] arm64: Add the arm64.nosve " Marc Zyngier
2022-06-27 17:08   ` Mark Brown
2022-06-27 15:18 ` [PATCH 0/6] arm64: Disabling SVE/SME from the command-line Mark Brown
2022-06-27 15:30   ` Marc Zyngier [this message]
2022-06-27 16:49     ` Mark Brown
  -- strict thread matches above, loose matches on Subject: below --
2022-06-27 15:13 Marc Zyngier

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