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Re: Which port for armv4l?



On 2016-08-10 12:54 -0400, Stefan Monnier wrote:
> 
> So in the OP's case, it seems that installing Debian with a kernel that
> emulates the missing instructions, is all it takes to get a working
> system, and then you can:
> - tweak /etc/dpkg/buildflags.conf to tell the
>   compiler to optimize for the armv4l architecture
> - use "apt-get -b source <packages>" to rebuild the
>   performance-sensitive packages with those flags.
> - then I guess you'd use dpkg to actually install those packages.

In principle this would work fine. But if it worked then debian armel
would already be built this way (we didn't _want_ to drop strongARM
support). The problem is that the compiler, when outputting code for
EABI (armel), does not support armv4, (due to boring stuff about thumb
interworking, atomics and the BX instruction). It's all documented
somewhere, probably in the those links that NeilW sent.

So in practice, you need to use the 'BX emulation' kernel patch
instead. I checked with the author (Marc Zyngier) this afternoon, and
apparently it works very well, but it is indeed not upstreamed
(rejected). (And I don't have a link to hand)

Wookey
-- 
Principal hats:  Linaro, Debian, Wookware, ARM
http://wookware.org/

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