[Ce-android-mainline] binder re-implementation

[Arnd Bergmann]

On Thursday 26 January 2012, Tim Bird wrote:
> On 01/26/2012 04:37 AM, Arnd Bergmann wrote:
> > On Wednesday 25 January 2012, Tim Bird wrote:
> >> I don't know if anything will come of it, but someone has gone to the
> >> trouble of starting a project to re-implement the binder driver,
> >> apparently in an effort to improve SMP performance.
> >>
> >> See
> >> http://groups.google.com/group/android-kernel/browse_frm/thread/c57874670e4decb1
> >>
> >> It's too early to tell if this project will yield usable results,
> >> but I thought it was worth preserving a reference to, for anyone
> >> who ends up working on binder.
> > 
> > I've looked briefly at it, and it doesn't seem to change the
> > kernel to user space interface at all, which would be the most
> > important thing to get right before worrying about implementation
> > details. I have no way to tell if the work on the binder
> > re-implementation is a good thing or not, but it seems to be
> > orthogonal to the cleanup on the kernel interface that we need
> > to get binder graduated from staging to a proper subsystem.
> 
> Since I don't have time to work on binder myself, I haven't
> pressed for details about what people would like to see changed
> in the kernel interfaces.  However, maybe a thumbnail sketch
> would be good.
> 
> Could you give us a quick rundown of the problems you see
> with the existing interfaces?  I'm not really trying to start
> a technical discussion here (as I don't have enough experience
> with binder to make any judgements or evaluate the critique).
> The lack of response might give the impression that the issues
> are being dropped in the bit bucket.  But I plan to at least
> record on the wiki the issues that may need addressing.

I sent a reply in December on this topic, see
http://lists.linuxfoundation.org/pipermail/ce-android-mainline/2011-December/000013.html

Most importantly, I think the binder needs to be changed
from a chardev driver with double-indirect ioctl commands
to an interface with system calls, each of them as simple
as possible while maintaining the functionality.

	Arnd