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Re: [PATCH-for-5.2] block/nvme: Fix nvme_submit_command() on big-endian
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From: |
Stefan Hajnoczi |
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Subject: |
Re: [PATCH-for-5.2] block/nvme: Fix nvme_submit_command() on big-endian host |
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Date: |
Wed, 28 Oct 2020 07:51:38 +0000 |
On Tue, Oct 27, 2020 at 05:04:07PM +0100, Philippe Mathieu-Daudé wrote:
> The Completion Queue Command Identifier is a 16-bit value,
> so nvme_submit_command() is unlikely to work on big-endian
> hosts, as the relevant bits are truncated.
>
> The "Completion Queue Entry: DW 2" describes it as:
>
> This identifier is assigned by host software when
> the command is submitted to the Submission
>
> As the is just an opaque cookie, it is pointless to byte-swap it.
The code does not make it clear that the missing byteswap is
intentional. Please either fix the byteswap (32 -> 16) or add code
comments explaining why the byteswap is not necessary.
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