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Date:   Tue, 11 Jul 2023 05:01:15 -0700
From:   Christoph Hellwig <hch@infradead.org>
To:     "Andreas Hindborg (Samsung)" <nmi@metaspace.dk>
Cc:     Christoph Hellwig <hch@infradead.org>,
        Ming Lei <ming.lei@redhat.com>,
        Damien Le Moal <dlemoal@kernel.org>,
        open list <linux-kernel@vger.kernel.org>,
        "open list:BLOCK LAYER" <linux-block@vger.kernel.org>,
        Minwoo Im <minwoo.im.dev@gmail.com>,
        Matias Bjorling <Matias.Bjorling@wdc.com>,
        gost.dev@samsung.com, Jens Axboe <axboe@kernel.dk>,
        Aravind Ramesh <Aravind.Ramesh@wdc.com>,
        Johannes Thumshirn <jth@kernel.org>,
        Hans Holmberg <Hans.Holmberg@wdc.com>
Subject: Re: [PATCH v6 1/3] ublk: add opcode offsets for DRV_IN/DRV_OUT
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On Tue, Jul 11, 2023 at 12:15:18PM +0200, Andreas Hindborg (Samsung) wrote:
> And yet they are somewhat similar, in the sense that they allow the user
> of a protocol to express semantics that is not captured in the
> established protocol. Uring command passthrough -> request passthrough
> -> vendor specific commands. They sort of map well in terms of what they
> allow the user to achieve. Or did I misunderstand something completely?

Well, there is a relationship, but it's one way.

Vendor specific command are basically always going to be used through
a passthrough interface, because they aren't standardized.

But most commands used through a passthrough interface are normal
standardized commands, just either used in a way not supported by
the normal Linux interface or just in creative ways.