Messages in this thread | | | Date | Fri, 18 May 2012 09:14:05 -0700 | Subject | Re: Urgent: x86-32 and GNU ld 2.22.52.0.1 | From | "H.J. Lu" <> |
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On Fri, May 18, 2012 at 8:56 AM, H. Peter Anvin <hpa@zytor.com> wrote: > I need an urgent opinion. It seems we have an epic mess on our hands. > > GNU ld 2.22.52.0.1 silently changed the semantics of section-relative > symbols that are part of otherwise empty sections, and silently changes > them to absolute. We rely on section-relative symbols staying > section-relative, and actually have several sections in the linker > script solely for this purpose.
That is I talked to you a couple days ago:
http://sourceware.org/bugzilla/show_bug.cgi?id=14052
> The postprocessor for the x86-32 kernel, relocs.c, currently doesn't > enforce its audited absolute symbols list. As part of the > tip:x86/trampoline rework, however, I made it error out rather that > silently producing bad output. > > Ingo has found that with this particular version of GNU ld, the error > triggers. I want to emphasize that this merely catches an error which > the current version of the tool would have allowed to silently go by, > which would have (possibly) caused a failure if the kernel was > subsequently booted in anything but its default location. > > There are a few ways we can deal with this, but I think we need to do > one or the other: > > 1. We can blacklist this version of GNU ld.
I think this is the best approach.
> 2. We can uprev the tool to the one from the tip:x86/trampoline work, > with error checking, and give it a list of symbols that should > be relative but may end up as absolute. We risk build errors for > some people if the list isn't complete. > 3. We do a minimal forward-port of the error checking into the current > tool. > 4. We add to the list of relative symbols in the current version of > the tool without adding the error checking. > > However, since it seems clear that we're silently producing corrupt > kernels out of the current build, I think we need a fix for this for 3.4. >
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