Re: PT_NOTE alignment, NT_GNU_PROPERTY_TYPE_0, glibc and gold

[Mark Wielaard <mark at klomp dot org>]

On Fri, Aug 17, 2018 at 08:10:15AM -0700, H.J. Lu wrote:
> On Thu, Aug 16, 2018 at 11:41 PM, Mark Wielaard <mark@klomp.org> wrote:
> > On Fri, Aug 17, 2018 at 08:20:53AM +0200, Florian Weimer wrote:
> >> But like you, I don't yet see the value of the 8-byte alignment.  We could
> >> decide that the current gold behavior is valid, fix glibc, and move on.
> >
> > Right. gold seems to produce normal GNU abi ELF Notes, which should
> > be accepted as is.
> 
> NT_GNU_PROPERTY_TYPE_0 should stay to follow gABI.

That doesn't make any sense. gABI doesn't have a concept of 32bit word
ELF notes that are 8-byte aligned. That is just a bug in ld when it
generates the note. It also doesn't make sense to generate GNU ELF notes
with slightly different padding added depending on type in the same ELF
file. That just creates confusion, causes you to define different
alignments of notes resulting in extra PT_LOAD segments and results in
bugs like we are discussing now where ELF note parsers fail to parse
some (valid) notes. Lets just agree that the gold linker is correct and
produces consistent GNU abi ELF notes. And lets just fix ld to do the same.

Thanks,

Mark