Kernel download site structure

[Nick]

Hi Antonio,

Quoth Antonio Grassi:
> Hello list. I'm working on the LibreWRT project [1] whish is based on
> OpenWRT [2]
> 
> The idea is to create an OpenWRT variant that would use only libre software.
> OpenWRT is composed of a bunch of scripts that download the kernel and the
> base system sources and compiles everything, producing a disk image.
> Different kernel versions are used for different target architectures.

Brilliant! I have a WRT54GS router myself, running OpenWRT, and
love to see more fun and freedom-oriented work done on it. (though 
I'm not sure if the free B43 firmware works yet - do provide 
instructions for this if it's possible sometime ;-))

> As part of this work, we added a build option. When set, the kernel to
> download and compile should be Linux-Libre instead of the blobbed one. I
> made a POC which worked ok, and now I'm working on a clean patch to submit
> upstream to OpenWRT.
> 
> The patch should ideally just change the URL used to download the kernel,
> but this seems a bit hard, 'cause the directory structure & naming differs
> between kernel.org and Libre Linux. Even worse, I see that some releases end
> in -libre, others in libre-1, libre-2, etc

Yes, this was tricky in the case of us at Gentoo, too. I ended up 
using 
http://www.fsfla.org/svnwiki/selibre/linux-libre/download/releases/LATEST-${DEBLOB_PV}.N/ 
(where DEBLOB_PV is eg 2.6.30). This always points to the latest 
libre version. One slight issue with this, though, is that if that 
symlink changes because there's a different libre version (doesn't 
happen too often), the checksums which are automatically cached by 
Gentoo will change so integrity checks might change. Looking at it 
again, though, if you're getting the kernel sources rather than the 
deblob scripts, you'll still have to keep track of the libre 
version.

The directory structure being slightly different was annoying for us 
too, but not difficult. Though as we now just apply the deblob 
script to a vanilla kernel, it's no longer an issue for us.

I don't know how the OpenWRT build system works, but if you could do 
as we do, so that one can choose to automatically run the deblob 
scripts against any available kernel by choosing an option, that'd 
be nicer as whatever kernel patches people want, deblobbing will be 
available. Also, using the script handily steps around the naming 
and directory structure issues.

> So I'm writing to the list to know if there's a logic behind the naming
> scheme of Linux Libre, so that I can determine which is the folder and the
> name of the tarball that should be used for a given version. E.g. if kernel
> version is 2.6.32.14 how to know I should
> download 2.6.32.14-libre1/linux-2.6.32.14-libre1.tar.bz2 ?

I believe the appended number to libre in the filename is to mark 
where there have been major changes to the deblob rules. There is 
mention of it somewhere in the archives (or just wait for a response 
from Alexandre).
 
> I'm also curious about the reasons for not mirroring the
> kernel.orgdirectory & naming conventions, could someone illustrate me
> about this?

Yes, for the record, this would have been useful for us too, before 
we switched to using the script directly. I suggest the project 
considers switching to a directory structure as kernel.org's, and 
ideally stable and predictable tarball URLs, so it's easier for 
people to write interesting scripts to automatically get your deblob 
goodness :-)

Nick
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