linux-kernel - Re: [PATCH, RFC] byteorder: sanity check toolchain vs kernel endianess

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Message-ID: <20190412145538.GA24473@lst.de>
Date:   Fri, 12 Apr 2019 16:55:38 +0200
From:   Christoph Hellwig <hch@....de>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Christoph Hellwig <hch@....de>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-arch <linux-arch@...r.kernel.org>, mick@....forth.gr,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH, RFC] byteorder: sanity check toolchain vs kernel
 endianess

On Fri, Apr 12, 2019 at 04:53:28PM +0200, Arnd Bergmann wrote:
> On Fri, Apr 12, 2019 at 4:36 PM Christoph Hellwig <hch@....de> wrote:
> >
> > When removing some dead big endian checks in the RISC-V code Nick
> > suggested that we should have some generic sanity checks.  I don't think
> > we should have thos inside the RISC-V code, but maybe it might make
> > sense to have these in the generic byteorder headers.  Note that these
> > are UAPI headers and some compilers might not actually define
> > __BYTE_ORDER__, so we first check that it actually exists.
> >
> > Suggested-by: Nick Kossifidis <mick@....forth.gr>
> > Signed-off-by: Christoph Hellwig <hch@....de>
> 
> Acked-by: Arnd Bergmann <arnd@...db.de>
> 
> Extra checking like this is good in general, but I'm not sure I see
> exactly what kind of issue one might expect to prevent with this:

I'm personally not worried at all. Just trying to respond to Nicks
review comment and make it reasonable generic if we have to have these
checks at all.  I personally would be ok without them, I just don't
want them hidden somewhere in the RISC-V code (RISC-V is always little
endian at least right now).