Messages in this thread |  | | From | Arnd Bergmann <> | Date | Sat, 27 Jan 2018 15:26:23 +0100 | Subject | Re: [PATCH 20/21] Kbuild, lto: Add Link Time Optimization support |
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On Sat, Jan 27, 2018 at 1:55 AM, Andi Kleen <ak@linux.intel.com> wrote: > On Sat, Jan 27, 2018 at 01:15:49AM +0100, Arnd Bergmann wrote: >> On Mon, Nov 27, 2017 at 10:34 PM, Andi Kleen <andi@firstfloor.org> wrote: >> > From: Andi Kleen <ak@linux.intel.com> >> > - Add a new LDFINAL variable that controls the final link >> > for vmlinux or module. In this case we call gcc-ld instead >> > of ld, to run the LTO step. >> >> When I tried this out on allmodconfig (following the lwn article), I ran into >> a number of warnings: > > Thanks for testing. Yes it's a known issue: during one module build > when modpost looks at the file it is still in LTO format, and > modpost doesn't understand the LTO symbol table. I had a patch > to teach it to it at some point, but it got lost somewhere. > The LLVM LTO patchkit has a different solution that actually > fixes the sequence to run modpost only after a LTO final link, > but I haven't gotten around to port that one. > > It seems to work already for the single file modules.
Ok, I see. I've turned off that warning now for testing.
What about this one:
kallsyms failure: relative symbol value 0xffffffff81000000 out of range in relative mode
I seem to get that all the time here, and have also disabled it for now, but it sounds important (and breaks the build).
Arnd
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