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From: Sasha Levin <sashal@kernel.org>
To: Nick Desaulniers <ndesaulniers@google.com>
Cc: "Ard Biesheuvel" <ardb@kernel.org>,
	"Greg KH" <gregkh@linuxfoundation.org>,
	"# 3.4.x" <stable@vger.kernel.org>,
	clang-built-linux <clang-built-linux@googlegroups.com>,
	"Jian Cai" <jiancai@google.com>, "Stefan Agner" <stefan@agner.ch>,
	"Catalin Marinas" <catalin.marinas@arm.com>,
	"Sami Tolvanen" <samitolvanen@google.com>,
	candle.sun@unisoc.com,
	"Miles Chen (陳民樺)" <miles.chen@mediatek.com>,
	"Stephen Hines" <srhines@google.com>,
	"Luis Lozano" <llozano@google.com>,
	"Sandeep Patil" <sspatil@google.com>,
	"Marc Zyngier" <maz@kernel.org>
Subject: Re: ARCH=arm LLVM_IAS=1 patches for 5.10, 5.4, and 4.19
Date: Tue, 16 Mar 2021 10:02:13 -0400	[thread overview]
Message-ID: <YFC6ZYvBfI/mFvaV@sashalap> (raw)
In-Reply-To: <CAKwvOdm6FXWVu-9YkQNNyoYmw+hkj1a7MQrRbWyUxsO2vDcnQA@mail.gmail.com>

On Mon, Mar 15, 2021 at 03:58:07PM -0700, Nick Desaulniers wrote:
>On Mon, Mar 15, 2021 at 10:53 AM Ard Biesheuvel <ardb@kernel.org> wrote:
>> You haven't explained why all this effort is justified to begin with.
>>
>> Who cares about being able to build 4.19 or 5.4 mainline with Clang 12
>> and IAS?
>
>Ah, sorry, ChromeOS and Android very much do so.  (Google's production
>kernels as well, though I don't think they have any 32b ARM machines).
>Android is already building 4.19+ with LLVM_IAS=1 for
>ARCH=arm64,x86_64,i686. ChromeOS is doing so for 5.4+ for
>ARCH=arm64,x86_64 as well.  I'm not sure precisely what's going on in
>prodkernel land, but I know they have LLVM_IAS=1 enabled for x86_64.
>So when Greg says this is "for no real users" I disagree.  Maybe no
>one is using LLVM_IAS=1 for ARCH=arm at this moment, but that was the
>point of the backports, to enable more distros to do so.

You can't both stay on a "stable" kernel because it's "stable", but
then expect a flow of new features. The users which you've mentioned
should be migrating to newer kernels instead of attempting to backport
features they care about to stable kernels.

-- 
Thanks,
Sasha

  parent reply	other threads:[~2021-03-16 14:02 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-11 19:32 ARCH=arm LLVM_IAS=1 patches for 5.10, 5.4, and 4.19 Nick Desaulniers
2021-03-12 10:12 ` Greg KH
2021-03-12 17:28   ` Nick Desaulniers
2021-03-13  4:07     ` Sasha Levin
2021-03-15  9:08       ` Greg KH
2021-03-15  9:12         ` Greg KH
2021-03-15  9:16           ` Greg KH
2021-03-15 10:37             ` Ard Biesheuvel
2021-03-15 17:43               ` Nick Desaulniers
2021-03-15 17:53                 ` Ard Biesheuvel
2021-03-15 22:58                   ` Nick Desaulniers
2021-03-15 23:19                     ` [PATCH 5.4.y] ARM: 9030/1: entry: omit FP emulation for UND exceptions taken in kernel mode Nick Desaulniers
2021-03-16  6:20                       ` Ard Biesheuvel
2021-03-16 16:59                         ` [PATCH 5.4 2/2] ARM: 9044/1: vfp: use undef hook for VFP support detection Nick Desaulniers
2021-03-19 10:06                           ` Greg KH
2021-03-19 20:14                             ` Nick Desaulniers
2021-03-20 11:04                               ` Greg KH
2021-03-16 14:02                     ` Sasha Levin [this message]
2021-03-15 19:06                 ` ARCH=arm LLVM_IAS=1 patches for 5.10, 5.4, and 4.19 Greg KH
2021-03-15 20:43                   ` Sasha Levin

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