From: David Laight <David.Laight@ACULAB.COM>
To: 'Arnd Bergmann' <arnd@arndb.de>,
Russell King <linux@armlinux.org.uk>,
Arnd Bergmann <arnd@kernel.org>
Cc: Rich Felker <dalias@libc.org>,
"linux-sh@vger.kernel.org" <linux-sh@vger.kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
"Linus Walleij" <linus.walleij@linaro.org>,
John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>,
"linux-mips@vger.kernel.org" <linux-mips@vger.kernel.org>,
Max Filippov <jcmvbkbc@gmail.com>,
Conor.Dooley <conor.dooley@microchip.com>,
guoren <guoren@kernel.org>,
"linux-csky@vger.kernel.org" <linux-csky@vger.kernel.org>,
"sparclinux@vger.kernel.org" <sparclinux@vger.kernel.org>,
"linux-riscv@lists.infradead.org"
<linux-riscv@lists.infradead.org>,
"Will Deacon" <will@kernel.org>, Christoph Hellwig <hch@lst.de>,
Helge Deller <deller@gmx.de>,
Geert Uytterhoeven <geert@linux-m68k.org>,
Vineet Gupta <vgupta@kernel.org>,
"linux-snps-arc@lists.infradead.org"
<linux-snps-arc@lists.infradead.org>,
"linux-xtensa@linux-xtensa.org" <linux-xtensa@linux-xtensa.org>,
Brian Cain <bcain@quicinc.com>,
"Lad, Prabhakar" <prabhakar.mahadev-lad.rj@bp.renesas.com>,
"linux-m68k@lists.linux-m68k.org"
<linux-m68k@lists.linux-m68k.org>,
"Paul Walmsley" <paul.walmsley@sifive.com>,
Stafford Horne <shorne@gmail.com>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
Neil Armstrong <neil.armstrong@linaro.org>,
Michal Simek <monstr@monstr.eu>,
"Thomas Bogendoerfer" <tsbogend@alpha.franken.de>,
"linux-parisc@vger.kernel.org" <linux-parisc@vger.kernel.org>,
"linux-openrisc@vger.kernel.org" <linux-openrisc@vger.kernel.org>,
"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Dinh Nguyen <dinguyen@kernel.org>,
"Palmer Dabbelt" <palmer@dabbelt.com>,
"linux-hexagon@vger.kernel.org" <linux-hexagon@vger.kernel.org>,
"linux-oxnas@groups.io" <linux-oxnas@groups.io>,
Robin Murphy <robin.murphy@arm.com>,
"David S . Miller" <davem@davemloft.net>
Subject: RE: [PATCH 15/21] ARM: dma-mapping: always invalidate WT caches before DMA
Date: Fri, 31 Mar 2023 11:01:54 +0000 [thread overview]
Message-ID: <a5f226ee509b4968a4c85784aedbedf4@AcuMS.aculab.com> (raw)
In-Reply-To: <a8a90181-a003-47a1-8257-fcbf55752249@app.fastmail.com>
From: Arnd Bergmann
> Sent: 31 March 2023 11:39
...
> Most architectures that have write-through caches (m68k,
> microblaze) or write-back caches but no speculation (all other
> armv4/armv5, hexagon, openrisc, sh, most mips, later xtensa)
> only invalidate before DMA but not after.
>
> OTOH, most machines that are actually in use today (armv6+,
> powerpc, later mips, microblaze, riscv, nios2) also have to
> deal with speculative accesses, so they end up having to
> invalidate or flush both before and after a DMA_FROM_DEVICE
> and DMA_BIDIRECTIONAL.
nios2 is a simple in-order cpu with a short pipeline
(it is a soft-cpu made from normal fpga logic elements).
Definitely doesn't do speculative accesses.
OTOH any one trying to run Linux on it needs their head examined.
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2023-03-31 11:03 UTC|newest]
Thread overview: 78+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-27 12:12 [PATCH 00/21] dma-mapping: unify support for cache flushes Arnd Bergmann
2023-03-27 12:12 ` [PATCH 01/21] openrisc: dma-mapping: flush bidirectional mappings Arnd Bergmann
2023-03-27 12:12 ` [PATCH 02/21] xtensa: dma-mapping: use normal cache invalidation rules Arnd Bergmann
2023-03-27 15:42 ` Max Filippov
2023-03-27 12:12 ` [PATCH 03/21] sparc32: flush caches in dma_sync_*for_device Arnd Bergmann
2023-03-27 12:13 ` [PATCH 04/21] microblaze: dma-mapping: skip extra DMA flushes Arnd Bergmann
2023-03-27 12:13 ` [PATCH 05/21] powerpc: dma-mapping: split out cache operation logic Arnd Bergmann
2023-03-27 12:13 ` [PATCH 06/21] powerpc: dma-mapping: minimize for_cpu flushing Arnd Bergmann
2023-03-27 12:56 ` Christophe Leroy
2023-03-27 13:02 ` Arnd Bergmann
2023-03-27 12:13 ` [PATCH 07/21] powerpc: dma-mapping: always clean cache in _for_device() op Arnd Bergmann
2023-03-27 12:13 ` [PATCH 08/21] riscv: dma-mapping: only invalidate after DMA, not flush Arnd Bergmann
2023-03-29 20:48 ` Conor Dooley
2023-03-30 7:10 ` Arnd Bergmann
2023-03-29 21:51 ` Jessica Clarke
2023-03-30 12:59 ` Lad, Prabhakar
2023-04-19 14:22 ` Palmer Dabbelt
2023-03-27 12:13 ` [PATCH 09/21] riscv: dma-mapping: skip invalidation before bidirectional DMA Arnd Bergmann
2023-03-29 20:16 ` Conor Dooley
2023-03-30 13:26 ` Lad, Prabhakar
2023-04-19 14:22 ` Palmer Dabbelt
2023-05-05 5:47 ` Guo Ren
2023-05-05 13:18 ` Arnd Bergmann
2023-05-06 7:25 ` Guo Ren
2023-05-06 7:53 ` Arnd Bergmann
2023-03-27 12:13 ` [PATCH 10/21] csky: dma-mapping: skip invalidating before DMA from device Arnd Bergmann
2023-03-27 13:37 ` Guo Ren
2023-03-27 12:13 ` [PATCH 11/21] mips: dma-mapping: skip invalidating before bidirectional DMA Arnd Bergmann
2023-03-27 12:13 ` [PATCH 12/21] mips: dma-mapping: split out cache operation logic Arnd Bergmann
2023-03-27 12:13 ` [PATCH 13/21] arc: dma-mapping: skip invalidating before bidirectional DMA Arnd Bergmann
2023-04-02 6:52 ` Vineet Gupta
2023-04-04 8:27 ` Shahab Vahedi
2023-04-06 9:01 ` Shahab Vahedi
2023-03-27 12:13 ` [PATCH 14/21] parisc: dma-mapping: use regular flush/invalidate ops Arnd Bergmann
2023-03-27 12:13 ` [PATCH 15/21] ARM: dma-mapping: always invalidate WT caches before DMA Arnd Bergmann
2023-03-31 9:01 ` Linus Walleij
2023-03-31 9:07 ` Russell King (Oracle)
2023-03-31 9:35 ` Russell King (Oracle)
2023-03-31 10:38 ` Arnd Bergmann
2023-03-31 11:01 ` David Laight [this message]
2023-03-31 11:08 ` Russell King (Oracle)
2023-03-31 12:32 ` Arnd Bergmann
2023-03-27 12:13 ` [PATCH 16/21] ARM: dma-mapping: bring back dmac_{clean,inv}_range Arnd Bergmann
2023-03-27 13:10 ` Russell King (Oracle)
2023-03-27 12:13 ` [PATCH 17/21] ARM: dma-mapping: use arch_sync_dma_for_{device,cpu}() internally Arnd Bergmann
2023-03-31 9:10 ` Linus Walleij
2023-03-31 12:48 ` Arnd Bergmann
2023-03-27 12:13 ` [PATCH 18/21] ARM: drop SMP support for ARM11MPCore Arnd Bergmann
2023-03-30 7:48 ` Neil Armstrong
2023-03-30 10:03 ` Arnd Bergmann
2023-03-30 16:40 ` Neil Armstrong
2023-03-30 8:12 ` Linus Walleij
2023-03-30 11:28 ` Joel Stanley
2023-03-31 12:54 ` Arnd Bergmann
2023-04-05 1:49 ` Joel Stanley
2023-03-30 11:51 ` Ard Biesheuvel
2023-03-31 17:09 ` Catalin Marinas
2023-03-27 12:13 ` [PATCH 19/21] ARM: dma-mapping: use generic form of arch_sync_dma_* helpers Arnd Bergmann
2023-03-27 12:13 ` [PATCH 20/21] ARM: dma-mapping: split out arch_dma_mark_clean() helper Arnd Bergmann
2023-03-27 12:48 ` Robin Murphy
2023-03-31 14:00 ` Arnd Bergmann
2023-03-31 15:12 ` Robin Murphy
2023-03-31 17:20 ` Arnd Bergmann
2023-03-27 15:01 ` Russell King (Oracle)
2023-03-31 14:06 ` Arnd Bergmann
2023-03-31 15:54 ` Russell King (Oracle)
2023-07-03 7:54 ` Geert Uytterhoeven
2023-07-06 14:11 ` Christoph Hellwig
2023-03-27 12:13 ` [PATCH 21/21] dma-mapping: replace custom code with generic implementation Arnd Bergmann
2023-03-27 22:25 ` Christoph Hellwig
2023-03-31 13:04 ` Arnd Bergmann
2023-03-30 14:06 ` Lad, Prabhakar
2023-04-13 12:13 ` Biju Das
2023-04-13 12:51 ` Arnd Bergmann
2023-06-27 16:52 ` Geert Uytterhoeven
2023-03-31 16:53 ` [PATCH 00/21] dma-mapping: unify support for cache flushes Catalin Marinas
2023-03-31 20:27 ` Arnd Bergmann
2023-05-25 7:46 ` Lad, Prabhakar
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=a5f226ee509b4968a4c85784aedbedf4@AcuMS.aculab.com \
--to=david.laight@aculab.com \
--cc=arnd@arndb.de \
--cc=arnd@kernel.org \
--cc=bcain@quicinc.com \
--cc=catalin.marinas@arm.com \
--cc=conor.dooley@microchip.com \
--cc=dalias@libc.org \
--cc=davem@davemloft.net \
--cc=deller@gmx.de \
--cc=dinguyen@kernel.org \
--cc=geert@linux-m68k.org \
--cc=glaubitz@physik.fu-berlin.de \
--cc=guoren@kernel.org \
--cc=hch@lst.de \
--cc=jcmvbkbc@gmail.com \
--cc=linus.walleij@linaro.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-csky@vger.kernel.org \
--cc=linux-hexagon@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-m68k@lists.linux-m68k.org \
--cc=linux-mips@vger.kernel.org \
--cc=linux-openrisc@vger.kernel.org \
--cc=linux-oxnas@groups.io \
--cc=linux-parisc@vger.kernel.org \
--cc=linux-riscv@lists.infradead.org \
--cc=linux-sh@vger.kernel.org \
--cc=linux-snps-arc@lists.infradead.org \
--cc=linux-xtensa@linux-xtensa.org \
--cc=linux@armlinux.org.uk \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=monstr@monstr.eu \
--cc=neil.armstrong@linaro.org \
--cc=palmer@dabbelt.com \
--cc=paul.walmsley@sifive.com \
--cc=prabhakar.mahadev-lad.rj@bp.renesas.com \
--cc=robin.murphy@arm.com \
--cc=shorne@gmail.com \
--cc=sparclinux@vger.kernel.org \
--cc=tsbogend@alpha.franken.de \
--cc=vgupta@kernel.org \
--cc=will@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).