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From: Jim Wilson <jimw@sifive.com>
Date: Tue, 07 Jan 2020 01:29:00 -0000
Message-ID: <CAFyWVaYqcvNuLM9oE2GYGN82CBGGHbYJz=cZQYGJNySzJzUbpA@mail.gmail.com>
Subject: Re: Math errors
To: Alistair Francis <alistair23@gmail.com>
Cc: Joseph Myers <joseph@codesourcery.com>, GNU C Library <libc-alpha@sourceware.org>
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On Thu, Jan 2, 2020 at 6:18 PM Alistair Francis <alistair23@gmail.com> wrote:
> There are a handful of math tests that seem to fail, but if I manually
> run the test a few times I will eventually get a pass. Any hints on
> what to do there?

There is a known bug in the RISC-V linux port where FP regs can leak
across fork and exec.  This is normally not a fatal problem, except
for some tests that assume that the FP exception flags are clear on
program start.  This can be false if they were set in the parent
process, which can cause some glibc math test failures.  This can
result in failures that appear/disappear when run manually versus from
the testsuite driver.  There are only about 5 tests that are affected.
The bug was finally fixed about a year and a half after I first
reported it.  That happened only a few months ago.  If you don't have
a recent enough version of the linux kernel you may not have the fix.

Jim