Messages in this thread |  | | | Date | Fri, 29 Oct 2010 13:15:55 -0700 | | From | "H. Peter Anvin" <> | | Subject | Re: [PATCH 2/2] jump label: disable due to compiler bug |
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On 10/29/2010 10:33 AM, Steven Rostedt wrote: >> >> Should this knowledge be builtin to the jump label enabling calculus? > > No, because we can't trust versions. We never know what home grown gcc a > kernel developer is using (and what has been backported or not). Thus > the only option is to have a builtin test we can do at compile time to > determine if the bug exists or not and decide then. > > Note, I'm currently running my last set of patches through ktest. When > it finishes (presumably with no issues), I'll post a pull request. >
I disagree with that assessment.
We know that if version >= 4.5.2 the problem has been fixed, and that for earlier versions we can't know if it's there, so just disable it for gcc < 4.5.2. The fix might have been backported, but it's not a big deal if the users of backported compilers don't see the full benefit -- it's only a problem during a limited time window anyway.
Admittedly it would be nice to have a header file or even a configuration file where the gcc version is tested and workarounds are centralized; then the backporters could put their own overrides in there.
-hpa
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