Right, we can tell it's a requirement for ARM, because Evan had to
change the Ur/Web implementation to maintain alignment, to get it
working on ARM. :)
I think it's best to apply Evan's alignment patch unconditionally, for
all architectures, and I'm hoping he can just send what he already
implemented.
On 05/07/2014 02:34 PM, Austin Seipp wrote:
FWIW, alignment is probably not only good for most non-Nehalem*
platforms, it is also a requirement for certain platforms like 32-bit
ARM, if I'm not mistaken. I believe AArch64 (64bit ARM) has also
lifted this restruction, but in general it's probably a decent one to
follow for portability I think.
* Intel Nehalem was the first Intel arch to allow very cheap unaligned
load/stores from what I remember, these days I'm not even sure how
much slower they are than aligned ones...
On Wed, May 7, 2014 at 1:25 PM, Adam Chlipala <[email protected]> wrote:
Neat! Would you mind contributing a patch to address this ARM issue?
(Presumably this is just the code you already tweaked, perhaps ideally using
some kind of preprocessor magic to decide if the alignment is necessary, or
maybe alignment is also good for performance on all platforms that should be
supported.)
On 05/07/2014 12:36 PM, Evan Danaher wrote:
On Wed, May 07, 2014 at 08:37:58AM -0400, Adam Chlipala wrote:
[snip]
I don't know if anyone has built Ur/Web servers for ARM, but I can't
think
of any reason why it wouldn't work right away. If there are issues,
they're
probably easy to fix. Certainly Ur/Web is used regularly with both
32-bit
and 64-bit x86.
I haven't finished any projects, but some of my playing around was on an
ARM machine running Ubuntu. IIRC, I had to tweak uw_malloc to always be
4-byte aligned, but aside from that I didn't run into any issues. (I
also didn't do anything particularly exciting, but the basics at least
worked without issue.)
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