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Re: ARM EABI port: minimum CPU choice

2006/6/12, Catalin Marinas <catalin.marinas@arm.com>:
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.

Short version:
Yes, Debian would be built in pure ARM mode anyway, but interworking
on v4t is important to one large user base.

Long version:
Embedded systems are one of ARM's main uses and I imagine people would
like to be have the option of building from standard Debian and
recompiling their biggest apps using Thumb until they get within their
permitted code size. This is important for v4t because it is currently
one of the bulk-market flavours: all of the china-japan-taiwan
projects I have heard from who are at the development stage for
imminent products are using v4t pieces cos that's what currently gives
the maximum poke per dollar.


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