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On 08/19/2016 11:15 AM, C Bergström wrote: |
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> On Fri, Aug 19, 2016 at 11:01 PM, Luca Barbato <lu_zero@g.o> wrote: |
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>> BTW is pathscale ready to be used as system compiler as well? |
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> |
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> I wish, but no. We have known issues when building grub2, glibc and |
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> the Linux kernel at the very least. Someone* did report a long time |
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> ago that with their unofficial port, were able to build/boot the |
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> NetBSD kernel. |
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> (*A community dev we trusted with our sources and was helping us with |
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> portability across platforms) |
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> |
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> The stuff with grub2 may potentially be fixed in the "near" future... |
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> the others are more tricky. In general if clang can do it, we have a |
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> strong chance as well. |
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> |
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> As a philosophy - "we" aren't really trying to be the best generic |
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> compiler in the world. We aim more on optimizing as much for known |
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> targets. So if by system you mean, a compiler that would produce an |
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> "OS" which only runs on a single class of hardware, then yeah it could |
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> work at some point in the future. Specifically, on x86 we default on |
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> host CPU optimizations. So on newer Intel hardware it's easy to get a |
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> binary that won't run on AMD or older 64bit Intel. |
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> |
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> More recently on ARMv8 - we turn on processor specific tuning. So |
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> while it may "run", the difference between APM's mustang and Cavium |
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> ThunderX is pretty big and running binaries intended for A and ran on |
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> B would certainly take a hit.. (this is just the tip of the iceberg) |
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> |
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> For general scalar OS code it isn't likely to matter... the real |
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> impact being like 1-10% difference (being very general.. it could be |
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> less or more in the real world..) |
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> |
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> For HPC codes or anything where you get loops or computationally |
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> complex - the gloves are off and I could see big differences... (again |
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> being general and maybe a bit dramatic for fun) |
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OK (actually fantastic!). Looking at the pathscale site pages and |
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github, perhaps a cheap arm embedded board where llvm is the centerpiece |
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of compiling a minimal system to entice gentoo-llvm testers, would be |
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possible in the near future?. I have a 96boards, HiKey arm64v8 that I |
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could dedicate to gentoo+armv8-llvm testing, if that'd help. [1] |
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Perhaps a baseline bootstrap iso (or such) version targeted at |
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llvm-centric testers on x86-64 or armv8 ? Skip grub2 and use grub-legacy |
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or lilo or (?), since there seems to be issues with llvm-grub2. |
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[1] http://dev.gentoo.org/~tgall/ |
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No matter how you slice it, from someone who is focused on building |
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minimized and embedded (bare metal) systems that are customized and |
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coalesced into a heterogeneous gentoo cluster for HPC, this is wonderful |
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news. Finally a vendor in the cluster space, with some vision and |
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common-sense, imho. Heterogeneous and open HPC is where is at, imho. If |
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there is a forum where the community and pathscale folks discuss issues, |
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point that out as I could not find one for deeper reading.... |
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hth, |
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James |
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