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From:   Sumit Garg <sumit.garg@linaro.org>
Date:   Thu, 25 Jun 2020 19:54:18 +0530
Message-ID: <CAFA6WYMF+JjrB9Cx9TdgDzMeQSvPZfMNapzD-MH4ALVoUoo1sQ@mail.gmail.com>
Subject: Re: [Tee-dev] [PATCHv8 1/3] optee: use uuid for sysfs driver entry
To:     James Bottomley <James.Bottomley@hansenpartnership.com>
Cc:     Jerome Forissier <jerome@forissier.org>,
        Maxim Uvarov <maxim.uvarov@linaro.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
        Arnd Bergmann <arnd@linaro.org>,
        "tee-dev @ lists . linaro . org" <tee-dev@lists.linaro.org>,
        Jason Gunthorpe <jgg@ziepe.ca>,
        linux-integrity@vger.kernel.org, peterhuewe@gmx.de
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On Wed, 24 Jun 2020 at 20:51, James Bottomley
<James.Bottomley@hansenpartnership.com> wrote:
>
> On Wed, 2020-06-24 at 16:17 +0530, Sumit Garg wrote:
> > Apologies for delay in my reply as I was busy with some other stuff.
> >
> > On Fri, 19 Jun 2020 at 20:30, James Bottomley
> > <James.Bottomley@hansenpartnership.com> wrote:
> [...]
> > > it's about consistency with what the kernel types mean.  When some
> > > checker detects your using little endian operations on a big endian
> > > structure (like in the prink for instance) they're going to keep
> > > emailing you about it.
> >
> > As mentioned above, using different terminology is meant to cause
> > more confusion than just difference in endianness which is manageable
> > inside TEE.
> >
> > And I think it's safe to say that the kernel implements UUID in big
> > endian format and thus uses %pUb whereas OP-TEE implements UUID in
> > little endian format and thus uses %pUl.
>
> So what I think you're saying is that if we still had uuid_be and
> uuid_le you'd use uuid_le, because that's exactly the structure
> described in the docs.  But because we renamed
>
> uuid_be -> uuid_t
> uuid_le -> guid_t
>
> You can't use guid_t as a kernel type because it has the wrong name?

Isn't the rename commit description [1] pretty clear about which is
the true UUID type from Linux point of view?

[1]
commit f9727a17db9bab71ddae91f74f11a8a2f9a0ece6
Author: Christoph Hellwig <hch@lst.de>
Date:   Wed May 17 10:02:48 2017 +0200

    uuid: rename uuid types

    Our "little endian" UUID really is a Wintel GUID, so rename it and its
    helpers such (guid_t).  The big endian UUID is the **only true** one, so
    give it the name uuid_t.  The uuid_le and uuid_be names are retained for
    now, but will hopefully go away soon.  The exception to that are the _cmp
    helpers that will be replaced by better primitives ASAP and thus don't
    get the new names.

    Also the _to_bin helpers are named to match the better named uuid_parse
    routine in userspace.

    Also remove the existing typedef in XFS that's now been superceeded by
    the generic type name.

    Signed-off-by: Christoph Hellwig <hch@lst.de>
    [andy: also update the UUID_LE/UUID_BE macros including fallout]
    Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
    Reviewed-by: Amir Goldstein <amir73il@gmail.com>
    Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
    Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

    Signed-off-by: Christoph Hellwig <hch@lst.de>

-Sumit

>
> James
>