From: Guo Ren <guoren@kernel.org>
To: Christoph Hellwig <hch@lst.de>
Cc: "Anup Patel" <anup.patel@wdc.com>,
"Atish Patra" <atish.patra@wdc.com>,
"Palmer Dabbelt" <palmerdabbelt@google.com>,
"Christoph Müllner" <christoph.muellner@vrull.eu>,
"Philipp Tomsich" <philipp.tomsich@vrull.eu>,
liush <liush@allwinnertech.com>,
wefu@redhat.com, "Wei Wu (吴伟)" <lazyparser@gmail.com>,
"Drew Fustini" <drew@beagleboard.org>,
linux-riscv <linux-riscv@lists.infradead.org>,
"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
taiten.peng@canonical.com, aniket.ponkshe@canonical.com,
heinrich.schuchardt@canonical.com, gordan.markus@canonical.com,
"Guo Ren" <guoren@linux.alibaba.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Arnd Bergmann" <arnd@arndb.de>,
"Palmer Dabbelt" <palmer@dabbelt.com>
Subject: Re: [RFC PATCH V4 1/6] riscv: pgtable: Add custom protection_map init
Date: Thu, 16 Sep 2021 07:52:09 +0800 [thread overview]
Message-ID: <CAJF2gTQ0Nbb7QCFjKdY223eHQjeV3_05Ub3N3LM7hvY38gizsg@mail.gmail.com> (raw)
In-Reply-To: <20210915074557.GA20024@lst.de>
Hi Christoph,
On Wed, Sep 15, 2021 at 3:46 PM Christoph Hellwig <hch@lst.de> wrote:
>
> On Sat, Sep 11, 2021 at 05:21:34PM +0800, guoren@kernel.org wrote:
> > From: Guo Ren <guoren@linux.alibaba.com>
> >
> > Some RISC-V CPU vendors have defined their own PTE attributes to
> > solve non-coherent DMA bus problems. That makes _P/SXXX definitions
> > contain global variables which could be initialized at the early
> > boot stage before setup_vm. The patch prevents compile errors.
>
> That sounds way to nice for someone who deliberatly ignores the
> specification and should definitively not go into the kernel
> commit log like this.
Okay. In the next version, I will optimize the wording.
>
> > This patch is similar to 316d097c4cd4 (x86/pti: Filter at
> > vma->vm_page_prot population) which give a choice for arch custom
> > implementation.
>
> How? To me it looks like a bad duplication of such functionality in
> a way that totally breaks abstractions. architectures really do not
> have any business changing protection_map.
D1's _P/SXXX definintion is different from riscv standard spec to get
non-coherency supported. It sets the highest bits and current spec
must keep zero. So we using a global variable struct in the _P/SXXX
definition to let vendors init their own _P/SXXX values during
bootstrap that is very early stage before setup_vm().
--
Best Regards
Guo Ren
ML: https://lore.kernel.org/linux-csky/
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next prev parent reply other threads:[~2021-09-15 23:52 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-11 9:21 [RFC PATCH V4 0/6] riscv: Add PBMT & DMA for D1 bringup guoren
2021-09-11 9:21 ` [RFC PATCH V4 1/6] riscv: pgtable: Add custom protection_map init guoren
2021-09-15 7:45 ` Christoph Hellwig
2021-09-15 23:52 ` Guo Ren [this message]
2021-09-11 9:21 ` [RFC PATCH V4 2/6] riscv: errata: pgtable: Add custom Svpbmt supported for Allwinner D1 guoren
2021-09-15 7:47 ` Christoph Hellwig
2021-09-16 0:48 ` Guo Ren
2021-09-16 7:31 ` Atish Patra
2021-09-11 9:21 ` [RFC PATCH V4 3/6] RISC-V: Support a new config option for non-coherent DMA guoren
2021-09-15 7:48 ` Christoph Hellwig
2021-09-16 1:20 ` Guo Ren
2021-09-16 4:39 ` Atish Patra
2021-09-16 6:09 ` Guo Ren
2021-09-11 9:21 ` [RFC PATCH V4 4/6] RISC-V: Implement arch_sync_dma* functions guoren
2021-09-15 7:50 ` Christoph Hellwig
2021-09-16 1:32 ` Guo Ren
2021-09-16 4:24 ` Anup Patel
2021-09-16 4:42 ` Atish Patra
2021-09-11 9:21 ` [RFC PATCH V4 5/6] riscv: errata: Support T-HEAD custom dcache ops guoren
2021-09-11 9:21 ` [RFC PATCH V4 6/6] riscv: soc: Add Allwinner SoC kconfig option guoren
2021-09-13 8:45 ` Maxime Ripard
2021-09-13 9:20 ` Guo Ren
2021-09-13 18:48 ` Randy Dunlap
2021-09-14 2:34 ` Guo Ren
2021-09-14 3:06 ` Randy Dunlap
2021-09-14 5:16 ` Anup Patel
2021-09-14 5:20 ` Randy Dunlap
2021-09-14 9:29 ` Arnd Bergmann
2021-09-14 10:07 ` Krzysztof Kozlowski
2021-09-14 10:13 ` Maxime Ripard
2021-09-14 12:09 ` Krzysztof Kozlowski
2021-09-14 13:02 ` Arnd Bergmann
2021-09-16 6:37 ` Guo Ren
2021-09-14 3:49 ` Heinrich Schuchardt
2021-09-14 5:16 ` Samuel Holland
2021-09-14 6:30 ` Heinrich Schuchardt
2021-09-14 7:20 ` Maxime Ripard
2021-09-14 9:26 ` Ben Dooks
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