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Date: Fri, 12 Sep 2014 13:53:11 -0700
From: Christoph Hellwig <hch@infradead.org>
Subject: Re: [RFC] Unicode/UTF-8 support for XFS
Message-ID: <20140912205311.GA11717@infradead.org>
References: <20140911203735.GA19952@sgi.com>
 <20140912100230.GB4267@dastard>
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To: Dave Chinner <david@fromorbit.com>
Cc: Ben Myers <bpm@sgi.com>, tinguely@sgi.com, olaf@sgi.com, xfs@oss.sgi.com

On Fri, Sep 12, 2014 at 08:02:30PM +1000, Dave Chinner wrote:
> > Implementation notes.
> > 
> > Strings are normalized using a trie that stores the relevant information.
> > The trie itself is part of the XFS module, and about 250kB in size. The
> > trie is not checked in: instead we add the source files from the Unicode
> > Character Database and a program that creates the header containing the
> > trie.
> 
> This is rather unappealing. Distros would have to take this code
> size penalty if they decide one user needs that support. The other
> millions of users pay that cost even if they don't want it.  And
> then there's validation - how are we supposed to validate that a
> 250k binary blob is correct and free of issues on every compiler and
> architecture that the kernel is built on?

The way this needs to be done is to have a separate module for the
tables, which XFS or other users then can symbol_get if and only if
a mount requires it.  The unicode tables should defintively be outside
of fs/xfs.

And please run this past lkml or -fsdevel, as people who actually
understand unicode and related issues are much more likely to be found
there than on the XFS list.

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