Date: Sun, 11 May 2014 17:20:55 -0300 From: "Matias A. Fonzo" <selk@...gora.org> To: musl@...ts.openwall.com Subject: Re: Broken GCC versions: 4.8.2 and 4.9.0 Hi dalias, On 2014-05-11 13:19, Rich Felker wrote: > On Sun, May 11, 2014 at 06:10:20PM +0200, Thomas Petazzoni wrote: >> >> On Sat, 10 May 2014 21:05:03 -0400, Rich Felker wrote: >> >> > It's come to my attention that GCC versions 4.8.2 and 4.9.0 are >> > performing invalid optimizations that result in a broken musl >> > libc.a/libc.so. It's not clear yet whether there's a good workaround, >> > or whether we should attempt to work around the problem, so for now, >> > please just be aware that these versions of GCC cannot be used to >> > compile musl. Using them to compile programs against musl should not >> > be a problem. I'll post more details later. The short version is that >> > it's making incorrect assumptions about the reachability of global >> > variables that have a local weak definition and an external strong >> > one. >> >> Hum, interesting. I've recently tested gcc 4.8.2 + musl on ARM, and >> gcc >> 4.9.0 + musl on i386, and I could boot a minimal musl+Busybox system >> under Qemu perfectly fine. Maybe the problem you refer to only affects >> certain parts of libc.a/libc.so? > > I've filed the bug report which you can see here: > > http://gcc.gnu.org/bugzilla/show_bug.cgi?id=61144 > > Something like the following command should confirm whether your build > is affected: > > nm src/stdio/fflush.o | grep stdout > > For broken gcc versions, there is no output. For non-broken ones, you > should see something like: > > 00000000 V __stdout_used I can confirm that I'm getting in Dragora (binutils 2.23.2, GCC 4.8.2 + musl 1.1.0): 0000000000000000 V __stdout_used I was getting scared.. :-)
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