Common ARM context save/restore code

[Nicolas Pitre]

On Thu, 7 Oct 2010, Vishwanath Sripathy wrote:

> Hi All,
> 
> Purpose of this email is to debate on the pros and cons of having a common
> ARM context save/restore code.
> Currently each SOC has its own way of saving/restoring ARM registers and
> there has been a proposal to have a common code for the same instead of
> duplicating the same in different places.

Hmmmmm, what?

Could you elaborate?  I'm afraid I'm not following you.

The kernel as I know it has a common code path to save/restore registers 
on context switch simply because all SOCs that I'm aware of all have the 
same general registers to save/restore on context switch.

There are exceptions for some specialized registers, such as the XScale 
WMMX registers, the Cirrus MaverickCrunch registers, the VFP registers 
or the emulated FPA registers, etc.  But those are nicely abstracted 
away from the common code through runtime registered thread notifier 
callbacks.


Nicolas