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Subject: Re: [PATCH v3 3/3] blk-crypto: show crypto capabilities in sysfs
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Eric Biggers <ebiggers@kernel.org>
Cc:     linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-api@vger.kernel.org, linux-scsi@vger.kernel.org,
        linux-mmc@vger.kernel.org, Hannes Reinecke <hare@suse.de>
References: <20211208013534.136590-1-ebiggers@kernel.org>
 <20211208013534.136590-4-ebiggers@kernel.org>
 <6ff4d074-7508-4f4c-de06-f36899668168@acm.org>
 <YbKT/lcp6iZ+lD4n@sol.localdomain> <YbL2uUqV0GWFOitE@kroah.com>
From:   Bart Van Assche <bvanassche@acm.org>
Message-ID: <cb29756b-8b21-5b4d-f107-b5573945d7ab@acm.org>
Date:   Fri, 10 Dec 2021 09:29:41 -0800
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On 12/9/21 10:42 PM, Greg Kroah-Hartman wrote:
> A single hex value makes sense to me.

Hi Greg,

I'm not enthusiast about this approach because:
(a) A single hex value can be confused with a number. Reporting a bitfield in
     hex format is not sufficient to prevent confusion with a number.
(b) No other block layer sysfs attribute follows this encoding scheme.
(c) This encoding enforces the restriction that data unit sizes are a power of
     two. Is there anything fundamental in encryption that restricts data unit
     sizes to a power of two? I don't know the answer myself.

Thanks,

Bart.