Re: pcb offset into uarea

[David Laight <david%l8s.co.uk@localhost>]

On Mon, Feb 17, 2014 at 06:39:26PM +0000, David Holland wrote:
> On Sun, Feb 16, 2014 at 09:41:08PM +0000, David Laight wrote:
>  > I'm adding code to i386 and amd64 to save the ymm registers on process
>  > switch - allowing userspace to use the AVX instructions.
>  > [ensuing crap about the u area]
> 
> Why put it in the u area at all? It's a legacy concept of little
> continuing value.

Certainly most of the stuff that is in the pcb could be put into the lwp
structure. Apart form the fp save area it isn't even very big.

Putting the FP save area at the low address of the kernel stack pages
saves you having to worry about how bit it is.
(for 'stack grows down' systems).

        David

-- 
David Laight: david%l8s.co.uk@localhost