Re: ARM EABI port: minimum CPU choice

[Catalin Marinas <catalin.marinas@arm.com>]

Hi Wookey,

Wookey <wookey@aleph1.co.uk> wrote:
> Debian emphasises supporting as much stuff as possible, over maximum speed.
> I think we should support armv4 if at all possible, and it seems that it is
> possible with the minor cost of a small slowdown (it would be useful to
> measure if it is significant at some point), and carrying a gcc
> patch.
>
> Strongarm support is important because currently a lot of debian buildd
> machines use it, and there is a lot of strongarm hardware out there that
> people might want to run Debian or debian-derived stuff on. 

Martin pointed me to the AemEabiPort wiki page that suggests that the
function return is "tst lr, #1; moveq pc, lr; bx lr" and this would
work on ARMv4t as well.

However, if the reason for this is to work on StrongARM (which doesn't
support Thumb, AFAIK) you could ban the Thumb use on ARMv4(t) and a
standard LDM or MOV PC, LR would return to Thumb code correctly on
ARMv5t. Debian would be built in ARM mode anyway and Thumb
interworking would only work correctly one ARMv5t (and later) cores.

-- 
Catalin