From: "Arnd Bergmann" <arnd@arndb.de>
To: "Linus Walleij" <linus.walleij@linaro.org>
Cc: "Michał Mirosław" <mirq-linux@rere.qmqm.pl>,
"Christoph Hellwig" <hch@lst.de>,
"Ulf Hansson" <ulf.hansson@linaro.org>,
"linux-mmc @ vger . kernel . org" <linux-mmc@vger.kernel.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mmc: core Drop BLK_BOUNCE_HIGH
Date: Sat, 10 Feb 2024 22:34:36 +0100 [thread overview]
Message-ID: <74835eb6-5625-4ff5-87ef-0edc96dba0fc@app.fastmail.com> (raw)
In-Reply-To: <CACRpkdYtUFAWweawpJquz2BUT81Ako0cZnKgZeyj8Jj93ru8fA@mail.gmail.com>
On Sat, Feb 10, 2024, at 20:38, Linus Walleij wrote:
> On Sat, Feb 10, 2024 at 12:58 PM Arnd Bergmann <arnd@arndb.de> wrote:
>> On Sat, Feb 10, 2024, at 00:41, Linus Walleij wrote:
>
>> > The only difference is where the CPU have to read/write the
>> > buffers really, before the change those were all guaranteed to
>> > be in lowmem (bounced there by the block core), now they can
>> > also be in highmem, but sg_miter will deal with it for sure.
>>
>> Yes, that was my point: The sg_miter() code is meant to
>> handle exactly this case with highmem data, but as far
>> as I can tell, that code path has never been tested on
>> 32-bit systems with highmem but without BLK_BOUNCE_HIGH.
>
> It's actually possible to enforce testing of highmem scatterlists
> to an MMC card (one need to be careful as this is destructive
> testing!)
> drivers/mmc/core/mmc_test.c
>
> ...but the one relevant target I have is a Kirkwood and it only
> has 128 MB of memory so highmem won't be exercised.
I think you can pass a vmalloc= command line option to the
kernel that will increase the size of the vmalloc are at
the expense of lowmem and give you some highmem instead.
Arnd
next prev parent reply other threads:[~2024-02-10 21:35 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-25 8:50 [PATCH] mmc: core Drop BLK_BOUNCE_HIGH Linus Walleij
2024-01-25 9:47 ` Arnd Bergmann
2024-02-09 22:35 ` Michał Mirosław
2024-02-09 23:41 ` Linus Walleij
2024-02-10 11:58 ` Arnd Bergmann
2024-02-10 19:38 ` Linus Walleij
2024-02-10 21:34 ` Arnd Bergmann [this message]
2024-01-25 14:38 ` Christoph Hellwig
2024-01-30 12:06 ` Ulf Hansson
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