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From: Christoph Hellwig <hch@lst.de>
To: Nick Kossifidis <mick@ics.forth.gr>
Cc: guoren@kernel.org, anup.patel@wdc.com, palmerdabbelt@google.com,
	arnd@arndb.de, wens@csie.org, maxime@cerno.tech,
	drew@beagleboard.org, liush@allwinnertech.com,
	lazyparser@gmail.com, wefu@redhat.com,
	linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
	linux-arch@vger.kernel.org, linux-sunxi@lists.linux.dev,
	Guo Ren <guoren@linux.alibaba.com>,
	Christoph Hellwig <hch@lst.de>
Subject: Re: [RFC PATCH v2 06/11] riscv: pgtable: Add DMA_COHERENT with custom PTE attributes
Date: Mon, 7 Jun 2021 08:19:18 +0200	[thread overview]
Message-ID: <20210607061918.GA24060@lst.de> (raw)
In-Reply-To: <610849b6f66e8d5a9653c9f62f46c48d@mailhost.ics.forth.gr>

On Sun, Jun 06, 2021 at 08:22:14PM +0300, Nick Kossifidis wrote:
> This patch violates the Privilege Spec section 4.4.1 that clearly states:
>
> "Bits63–54 are reserved for future standard use and must be zeroed by 
> software for forward compatibility"
>
> Standard use means that valid values can only be defined by the Priv. Spec, 
> not by the vendor (otherwise they'd be marked as "custom use" or "platform 
> use"), and since they "must" be zeroed by software we 'll be violating the 
> Privilege Spec if we do otherwise.

Yes, that is why I think it is a no-go.

  reply	other threads:[~2021-06-07  6:19 UTC|newest]

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-06  9:03 [RFC PATCH v2 00/11] riscv: Add DMA_COHERENT support for Allwinner D1 guoren
2021-06-06  9:03 ` [RFC PATCH v2 01/11] riscv: asid: Use global mappings for kernel pages guoren
2021-06-06  9:03 ` [PATCH V5 1/3] riscv: " guoren
2021-06-06  9:03 ` [PATCH V5 2/3] riscv: Add ASID-based tlbflushing methods guoren
2021-06-06 14:38   ` Christoph Hellwig
2021-06-06  9:03 ` [RFC PATCH v2 02/11] riscv: asid: " guoren
2021-06-06  9:04 ` [RFC PATCH v2 03/11] riscv: asid: Optimize tlbflush coding convention guoren
2021-06-06  9:04 ` [PATCH V5 3/3] riscv: tlbflush: Optimize " guoren
2021-06-06  9:04 ` [RFC PATCH v2 04/11] riscv: pgtable: Fixup _PAGE_CHG_MASK usage guoren
2021-06-06  9:04 ` [RFC PATCH v2 05/11] riscv: pgtable: Add custom protection_map init guoren
2021-06-06  9:04 ` [RFC PATCH v2 06/11] riscv: pgtable: Add DMA_COHERENT with custom PTE attributes guoren
2021-06-06 14:39   ` Christoph Hellwig
2021-06-06 15:08     ` Guo Ren
2021-06-06 17:22   ` Nick Kossifidis
2021-06-07  6:19     ` Christoph Hellwig [this message]
2021-06-06  9:04 ` [RFC PATCH v2 07/11] riscv: cmo: Add dma-noncoherency support guoren
2021-06-06  9:04 ` [RFC PATCH v2 08/11] riscv: cmo: Add vendor custom icache sync guoren
2021-06-06  9:04 ` [RFC PATCH v2 09/11] riscv: soc: Initial DTS for Allwinner D1 NeZha board guoren
2021-06-06 16:26   ` Jernej Škrabec
2021-06-06 17:05     ` Guo Ren
2021-06-07  3:44     ` Guo Ren
2021-06-07  7:27       ` Maxime Ripard
2021-06-07  7:53         ` Guo Ren
2021-06-07  7:24   ` Maxime Ripard
2021-06-07  8:07     ` Guo Ren
2021-06-14 15:33       ` Maxime Ripard
2021-06-14 16:28         ` Guo Ren
2021-06-14 16:31           ` Jernej Škrabec
2021-06-06  9:04 ` [RFC PATCH v2 10/11] riscv: soc: Add Allwinner SoC kconfig option guoren
2021-06-07  7:19   ` Maxime Ripard
2021-06-07  7:27     ` Arnd Bergmann
2021-06-07  7:45       ` Guo Ren
2021-06-07  7:43     ` Guo Ren
2021-06-07 12:12       ` Maxime Ripard
2021-06-07 12:39         ` Guo Ren
2021-06-06  9:04 ` [RFC PATCH v2 11/11] riscv: soc: Allwinner D1 GMAC driver only for temp use guoren
2021-06-06 10:50   ` Andre Przywara
2021-06-06 15:32     ` Guo Ren
2021-06-06 15:39       ` Jernej Škrabec
2021-06-06 15:41         ` Guo Ren
2021-06-06 16:16   ` Arnd Bergmann
2021-06-06 16:32     ` Jernej Škrabec
2021-06-06 16:53       ` Guo Ren
2021-06-06 16:53     ` Guo Ren
2021-06-06 16:29 ` [RFC PATCH v2 00/11] riscv: Add DMA_COHERENT support for Allwinner D1 Jernej Škrabec
2021-06-06 16:54   ` Guo Ren
2021-06-06 17:14     ` Jernej Škrabec
2021-06-06 23:42       ` Guo Ren
2021-06-07  3:44 ` Anup Patel
2021-06-07  4:36   ` Guo Ren

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