Advertisement
Front, Kernel, Security, Distributions, Development. See your byline here on LWN.net.
| |||||||||||||
|
| |||||||||||||
Tell this to Intel!Tell this to Intel!Posted Aug 14, 2009 4:44 UTC (Fri) by khim (guest, #9252)In reply to: Tell this to Intel! by nix Parent article: A default desktop for openSUSE?
Every closed-source thing would also break and need recompilation (unless glibc took special measures to keep non-relinked stuff working against an old-ABI version of libm, and why would it? ) Why not? GlibC developers already introduced symbol visibility and versioning mechanisms in version 2.1 to solve this problem - and it works (there were quite a few changes in GlibC ABI over the years - all 99%- backward compatible; it's rare to see program which works with GLibC 2.x but not with GLibC 2.x+1 if x is at least "1"). Biggest win of "-msse2 -mfpmath=sse" mode is not fact that it's faster (it's roughly the same in speed) but the fact that it generates predictable code! Your program works the same way with -O0 and with -O2, it conforms to IEEE 754, etc. If you are doing a lot of math the benefits are enormous so you should switch and if not then you don't have a lot of FP in interfaces and/or exported variables so switch is no big deal...
(Log in to post comments)
Tell this to Intel! Posted Aug 14, 2009 7:26 UTC (Fri) by nix (subscriber, #2304) [Link]
So, you suggest... what? Versioning *every symbol* in *every shared
library* that uses a double anywhere in its interfaces? That's going to fly. (I wish symbol versioning were used more widely, but let's face it, upstreams mostly don't care and just stick to older techniques.)
Not exactly Posted Aug 14, 2009 9:29 UTC (Fri) by khim (guest, #9252) [Link] So, you suggest... what? Versioning *every symbol* in *every shared library* that uses a double anywhere in its interfaces? You only need this for libraries used by closed-source programs. Everything else can be just recompiled (with usual bump of library version). It's not a rocket science...
Not exactly Posted Aug 15, 2009 10:24 UTC (Sat) by nix (subscriber, #2304) [Link]
It's not rocket science, but still the upstreams of most major shared
libraries would simply laugh at you for suggesting it (except Ulrich, who'd snap at you instead).
|
|
||||||||||||