Re: [Xen-devel] [PATCH v3 13/23] XENVER_build_id: Provide ld-embedded build-ids (v10)

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Wed, Feb 24, 2016 at 07:13:11PM +0000, Andrew Cooper wrote:
> On 24/02/16 18:52, Konrad Rzeszutek Wilk wrote:
> >>> diff --git a/xen/arch/arm/xen.lds.S b/xen/arch/arm/xen.lds.S
> >>> index f501a2f..5cf180f 100644
> >>> --- a/xen/arch/arm/xen.lds.S
> >>> +++ b/xen/arch/arm/xen.lds.S
> >>> @@ -22,6 +22,9 @@ OUTPUT_ARCH(FORMAT)
> >>>  PHDRS
> >>>  {
> >>>    text PT_LOAD /* XXX should be AT ( XEN_PHYS_START ) */ ;
> >>> +#if defined(BUILD_ID)
> >>> +  note PT_NOTE ;
> >>> +#endif
> >>>  }
> >>>  SECTIONS
> >>>  {
> >>> @@ -53,6 +56,16 @@ SECTIONS
> >>>          _erodata = .;          /* End of read-only data */
> >>>    } :text
> >>>  
> >>> +#if defined(BUILD_ID)
> >>> +  .note : {
> >>> +       __note_gnu_build_id_start = .;
> >>> +       *(.note.gnu.build-id)
> >>> +       __note_gnu_build_id_end = .;
> >>> +       *(.note)
> >>> +       *(.note.*)
> >>> +  } :text
> >>> +#endif
> >> This data really should be contained inside rodata.
> > I get (I replace :text with :rodata) and got:
> > ld: section `.note' assigned to non-existent phdr `rodata'
> >
> > Which makes sense as there are only two PHDRS. Where you suggesting that
> > the .note should be part of the .rodata section? Jan wanted this to be
> > in its own section (.note).
> >
> > Are you suggesting to add another one PHDR? (If so, then mkelf32 has to be 
> > modified,
> > and for EFI I think it will have to have some #ifdef machinery to make it 
> > work).
> 
> I was just suggesting moving _erodata down a little to cover .note

Which oddly enough is only in ARM builds. Done!

> 
> Whatever happens patching-wise, this build ID is constant and will want
> to remain so.
> 
> ~Andrew

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