Re: [gentoo-dev] [GLEP] Use EAPI-suffixed ebuilds (.ebuild-EAPI)

[Donnie Berkholz <dberkholz@gentoo.org>]

On 10:43 Thu 20 Dec     , Jan Kundrát wrote:
> Donnie Berkholz wrote:
> > Looking at my kernel config, ext3 and reiser explicitly support
> > xattrs, and I see jfs and xfs have acls and security labels, which
> > might be usable.
> 
> Extended attributes can be turned off during compile time for each
> filesystem you mentioned.

And?

If you turn off features you need, things break. There's nothing new 
about that. If you disable ext3 support in your kernel, you can't mount 
an ext3 partition and you'll get an error during boot about not finding 
the root.

> NFSv3 doesn't support them (yes, I do share $PORTDIR).

While doing a search about this, I came across a page on the Beagle site 
describing how Beagle deals with a similar issue that says:

 "Extended attributes are used by Beagle to keep track of which files 
  have been indexed and which need to be re-indexed. There is a 
  sqlite-based fallback which is a bit slower, so it is recommended that 
  you do use extended attributes. ...

 "Your kernel will need support for extended attributes on the filesystem 
  you are indexing. If you are using XFS or JFS, extended attributes are 
  always enabled and you can skip this section and move on to Installing 
  prerequisites. For Reiser3, ext2 and ext3 filesystems, the default 
  kernel config does not enable the attributes. ...

 "Also note that neither Reiser4 nor NFS support extended attributes, so 
  the sqlite-based fallback will be used by default."

The idea of the sqlite-based fallback is what's interesting here.

> Also note that in some circumstances like when running in a
> virtualized environment, imposing additional requirements on the kernel
> might be problematic.

Why's that? Here's some performance tests from 3 years ago on a 2.6.10 
kernel that hopefully have improved in the meanwhile:

http://lwn.net/Articles/112566/

> It wouldn't be great to require extended attributes for each and every 
> Gentoo box...

Why not?

Thanks,
Donnie
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