From: Christoph Hellwig <hch@infradead.org>
To: Lauri Kasanen <cand@gmx.com>
Cc: Christoph Hellwig <hch@infradead.org>,
linux-mips@vger.kernel.org, tsbogend@alpha.franken.de,
axboe@kernel.dk, linux-block@vger.kernel.org,
Keith Busch <kbusch@kernel.org>
Subject: Re: [PATCH v9] block: Add n64 cart driver
Date: Fri, 22 Jan 2021 17:08:28 +0000 [thread overview]
Message-ID: <20210122170828.GA237009@infradead.org> (raw)
In-Reply-To: <20210122185619.980fa4f713b8f57528c3af9e@gmx.com>
On Fri, Jan 22, 2021 at 06:56:19PM +0200, Lauri Kasanen wrote:
> > What alignment does the hardware require?
>
> It requires 8-byte alignment, but the buffer must also be physically
> contiguous.
If you want a single contiguous buffer you must use the
blk_queue_max_segments() API to ask for a single contiguous segment.
> I grepped around, but apparently no driver under drivers/block does
> direct DMA to the bio buffer. They all use their own buffer and memcpy,
> like this patch. ps3vram, ps3disk, amiflop, etc etc.
>
> If all existing drivers use their own buffer, why is a different
> approach required for new drivers?
That selections is a bunch of weirdo legacy drivers. If you want
to look at something reasonably modern but still simple take a look
at drivers/block/virtio_blk.c.
next prev parent reply other threads:[~2021-01-22 17:10 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-22 9:00 [PATCH v9] block: Add n64 cart driver Lauri Kasanen
2021-01-22 11:17 ` Christoph Hellwig
2021-01-22 13:58 ` Lauri Kasanen
2021-01-22 16:18 ` Christoph Hellwig
2021-01-22 16:23 ` Lauri Kasanen
2021-01-22 16:39 ` Christoph Hellwig
2021-01-22 16:56 ` Lauri Kasanen
2021-01-22 17:08 ` Christoph Hellwig [this message]
2021-01-22 17:11 ` Keith Busch
2021-01-22 18:01 ` Lauri Kasanen
2021-01-22 18:20 ` Christoph Hellwig
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