Re: Restructuring trapframe

[Matt Thomas <matt%3am-software.com@localhost>]

On Sep 20, 2013, at 12:20 AM, Martin Husemann <martin%duskware.de@localhost> 
wrote:

> On Thu, Sep 19, 2013 at 05:39:17PM -0700, Matt Thomas wrote:
>> The disadvantage is that for pre-ARMv6 it makes pull the frame more
>> difficult since have SPSR last isn't easy to deal with.  But pushing
>> the initial frame is easier.
> 
> Do we have to have the same layout for all arm versions? I assume only
> very few userland programs/ libs will know aobut it, if at all.

It depends.  If a kernel can be compiled for both pre-armv6 and armv6+
then it needs to share a common trapframe.  Otherwise they could be
different and let the compiler deal with the differences.  One alternative
is to only use the new trapframe for armv6 and later and default to the
older trapframe for any kernel that incorporates pre-armv6.