Re: [PATCH v8 4/4] fs: unicode: Add utf8 module and a unicode layer

From: "Theodore Ts'o" <tytso@mit.edu>
To: Gabriel Krisman Bertazi <krisman@collabora.com>
Cc: Shreeya Patel <shreeya.patel@collabora.com>,
	Christoph Hellwig <hch@infradead.org>,
	adilger.kernel@dilger.ca, jaegeuk@kernel.org, chao@kernel.org,
	ebiggers@google.com, drosen@google.com, ebiggers@kernel.org,
	yuchao0@huawei.com, linux-ext4@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	linux-f2fs-devel@lists.sourceforge.net,
	linux-fsdevel@vger.kernel.org, kernel@collabora.com,
	andre.almeida@collabora.com
Subject: Re: [PATCH v8 4/4] fs: unicode: Add utf8 module and a unicode layer
Date: Wed, 28 Apr 2021 10:12:59 -0400	[thread overview]
Message-ID: <YIlta1Saw7dEBpfs@mit.edu> (raw)
In-Reply-To: <87bl9z937q.fsf@collabora.com>

On Tue, Apr 27, 2021 at 11:06:33AM -0400, Gabriel Krisman Bertazi wrote:
> > I think the better argument to make is just one of simplicity;
> > separating the Unicode data table from the kernel adds complexity.  It
> > also reduces flexibility, since for use cases where it's actually
> > _preferable_ to have Unicode functionality permanently built-in the
> > kernel, we now force the use of some kind of initial ramdisk to load a
> > module before the root file system (which might require Unicode
> > support) could even be mounted.
> 
> FWIW, embedding FW images to the kernel is also well supported.  Making
> the data trie a firmware doesn't make a ramdisk more of a requirement
> than the module solution, I think.

I don't think we support building firmware directly into the kernel
any more.  We used to, but IIRC, there was the feeling that 99.99% of
the time, firmware modules were not GPL compliant, and so we ripped
out that support.

So my point was with the module support, it's *optional* that it be
compiled as a module, which is convenient for those use cases, such as
for example a mobile handset --- where there is no need for modules
since the hardware doesn't change, and so modules and an initrd is
just unnecessary complexity --- and firmware, which would make an
initial ramdisk mandatory if you wanted to use the casefold feature.

Put another way, the only reason why putting the unicode tables in a
module is to make life easier for desktop distros.  For mobile
handsets, modules are an anti-feature, which is why there was no call
for supporting this initially, given the initial use case for the
casefold feature.

Cheers,

					- Ted