Re: What integer type should ELF note header have?

[Mark Wielaard <mark@klomp.org>]

On Wed, 2017-12-13 at 10:09 -0800, H.J. Lu wrote:
> On Wed, Dec 13, 2017 at 5:57 AM, Mark Wielaard <mark@klomp.org>
> wrote:
> > On Mon, 2017-12-11 at 04:11 -0800, H.J. Lu wrote:
> > > Note segments/sections with 8 byte alignment should use Elf64_Nhdr64.
> > > If we want to do it, we should do it now before
> > > NT_GNU_PROPERTY_TYPE_0
> > > notes with the existing Elf64_Nhdr are generated by GCC 8 with
> > > -fcf-protection -mcet.
> > 
> > Yes, I think having a new note type is the way to go, if we want to
> > change the alignment requirements.
> > 
> > BTW. What is the reason you need 8 byte aligned notes?
> 
> NT_GNU_PROPERTY_TYPE_0 can have 64-bit integer properties
> in 64-bit objects.  They should be aligned to 8 bytes.

Not necessarily. You can have not naturally aligned data in files. ELF
files are cross architectures, so you have to account for different
alignments and endian issues anyway. Is there a specific property of
these 64-bit integers that require them to be 8 byte aligned in the
note descriptor data?

Thanks,

Mark