Contributing to the kernel video drivers

[Bertram Scharpf]

Hi,

On Monday, 28. Dec 2015, 18:36:26 +0100, Jean-Sébastien Pédron wrote:
> My proposal is that we continue to work on GitHub, namely in:
> https://github.com/freebsd/freebsd-base-graphics
> 
> [...]
> 
> Now, the complicated part is how to coordinate the work.
> 
> I believe the milestones should be versions of Linux. For instance, the
> next one on the road is Linux 3.9. We have DRM core and two drivers to
> sync and I think we should try to keep the whole DRM in sync (and not
> have i915 at 3.15 and Radeon at 3.13 for instance). Until now, I updated
> our DRM on a file-by-file basis: I took a file from Linux 3.8 and ported
> it to FreeBSD from scratch, by keeping an eye on the current FreeBSD
> copy. Therefore, I jumped from whatever version we were at straight to
> 3.8, at the high cost of an unbuildable kernel before the very end.
> 
> Another approach is to update on a commit-by-commit basis: we take all
> commits between 3.8 and 3.9 and apply them in order. The downside is
> that we could port code which is rewritten or removed 10 commits later.
> 
> In both cases, we need a complete review of the code before it's
> committed to HEAD: a comparison to HEAD to make sure we don't drop
> needed code, a comparison to Linux to make sure the update is complete.
> 
> An easy way to share the work is to split drivers: someone updates
> Radeon, someone else updates i915, a third contributor handles DRM.
> Still, this is not very parallel. If we go with the file-by-file update,
> it's very easy to parallelize further. With the commit-by-commit
> approach, it's complicated because it's obviously serialized.
> 
> Again, if we go with the file-by-file method, we could jump to a later
> version of Linux instead of doing one at a time. It's even more
> dangerous because we have more chance of breaking/loosing something
> because of the gap between the last update and the next one.

As I am not actually experienced in kernel hacking, it is
difficult for me to give a qualified answer here. Probably
writing file-by-file needs a higher level of discipline what
I regard as an advantage.

Because I am a kernel noob, I depend on detailed
instructions for the beginning. These perhaps can be
expressed easier with the file-by-file method.

Bertram

-- 
Bertram Scharpf
Stuttgart, Deutschland/Germany
http://www.bertram-scharpf.de