On Sat, 2012-11-10 at 18:28 +0000, Steve McIntyre wrote: > To explain for people who may not know: the benefit of x32 is that it > gives a non-shit 32-bit x86 ABI. i386 is *awful* as a processor to > target for many reasons, horrendously starved of registers. amd64 > (x86_64/x64) fixed this *and* added 64-bit support, which helped a > lot. amd64 typically gives much better performance on processor-heavy > workloads than i386 due to the increased register space, but this > improved is offset a little by the cost of the larger pointers taking > more cache space. x32 is an attempt to get the benefit of the better > register set without killing cache so much.
IIRC x32 also defaults to an amd64 style register-based calling convention instead of the stack based convention used the i386 ABI. I bet the effects of this are pretty interesting too. It's long been the case that kernel side, which doesn't have to worry about the calling convention ABI, has opted for -mregparm=3 on i386. Ian. -- Ian Campbell BOFH excuse #240: Too many little pins on CPU confusing it, bend back and forth until 10-20% are neatly removed. Do _not_ leave metal bits visible!
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