On Tue, Mar 23, 2021 at 9:36 AM Sean Christopherson <[email protected]> wrote: > > On Tue, Mar 23, 2021, Sami Tolvanen wrote: > > On Mon, Mar 22, 2021 at 4:44 PM Sean Christopherson <[email protected]> > > wrote: > > > > > > Merge module sections only when using Clang LTO. With gcc-10, merging > > > sections does not appear to update the symbol tables for the module, > > > e.g. 'readelf -s' shows the value that a symbol would have had, if > > > sections were not merged. > > > > I'm fine with limiting this to LTO only, but it would be helpful to > > understand which sections are actually getting merged here. > > It doesn't appear to matter which sections get merged, the tables only show > the > correct data if there is no merging whatsoever, e.g. allowing merging for any > one of the four types (.bss, .data, .rodata and .text) results in breakage. > AFAICT, merging any sections causes the layout to change and throw off the > symbol tables.
Thanks for the clarification. I can reproduce this issue with gcc + bfd if any of the sections are merged, but gcc + lld produces valid symbol tables. Perhaps someone more familiar with bfd can comment on whether this is a bug or a feature, and if there's a flag we can pass to bfd that would fix the issue. In the meanwhile, this patch looks like a reasonable workaround to me. Reviewed-by: Sami Tolvanen <[email protected]> Tested-by: Sami Tolvanen <[email protected]> Sami
