Date: Mon, 12 Jun 2017 11:03:32 +0200 From: Szabolcs Nagy <nsz@...t70.net> To: musl@...ts.openwall.com Subject: Re: [PATCH] s390x: Add single instruction math functions * David Edelsohn <dje.gcc@...il.com> [2017-06-11 22:46:09 -0400]: > On Sun, Jun 11, 2017 at 6:19 AM, Szabolcs Nagy <nsz@...t70.net> wrote: > > * Rich Felker <dalias@...c.org> [2017-06-10 22:20:44 -0400]: > >> On Sat, Jun 10, 2017 at 05:48:05PM -0400, David Edelsohn wrote: > >> > When I worked with Bobby Bingham to create the s390x port of Musl, I > >> > said that he could assume newer processors. Also, I don't believe > >> > that LLVM supports the earlier processors. I believe that he assumed > >> > some more recent instructions in other parts of the code. > >> > >> That seems doubtful; the amount of asm in musl is minimal and unlikely > >> to benefit from later ISA levels; all the instructions I see look like > >> very basic stuff that would always have been available. > >> > >> Now, what likely is accurate is your claim that nobody is using musl > >> on lower ISA levels, so maybe it doesn't matter. > > > > well i am using s390x musl with lower isa level for compile tests > > > > and it seems gas rejects unrecognized opcodes so the new inline > > asm does not compile for me. > > > > i think either musl configure should make sure the cc targets > > the right isa level or the code should handle it with ifdefs > > I have asked the IBM toolchain team how to distinguish the > architecture level at compile time, or at least distinguish support > for the FP rounding instruction. > > Are you actually running s390x musl on a system earlier than z196 > architecture level? The public IBM LinuxONE Cloud is running on a z13 > system, many generations newer than even z196. > no, i only have a cross compiler, but since the toolchain build script uses default settings i get z900 arch, if that's not good then gcc config default should be fixed for musl. > The following IBM table of supported and tested systems > > https://www-03.ibm.com/systems/z/os/linux/resources/testedplatforms.html > > shows that RHEL 7 and SLES 12 require at least z196, and Ubuntu 16.04 > requires at least zEC12. > > I can't find any official hardware requirements description for Alpine > Linux. I tend to doubt that user would run it on older hardware, > especially hardware no longer supported by other, modern Linux > distributions. > > Building musl libc on older hardware is a nice accomplishment, but > investing effort and complexity to maintain support probably isn't > useful to any musl libc user and probably isn't a productive use of > developer resources. > > I will continue to inquire if there is a simple technique to accomplish this. > > Thanks, David
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