Re: [PATCH v3 1/2] xen/build: put image header into a separate section

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Tue, Mar 08, 2022 at 04:08:53PM +0100, Jan Beulich wrote:
> On 08.03.2022 15:18, Roger Pau Monné wrote:
> > On Tue, Mar 08, 2022 at 02:57:23PM +0100, Jan Beulich wrote:
> >> On 08.03.2022 14:49, Roger Pau Monne wrote:
> >>> So it can be explicitly placed ahead of the rest of the .text content
> >>> in the linker script (and thus the resulting image). This is a
> >>> prerequisite for further work that will add a catch-all to the text
> >>> section (.text.*).
> >>>
> >>> Note that placement of the sections inside of .text is also slightly
> >>> adjusted to be more similar to the position found in the default GNU
> >>> ld linker script.
> >>>
> >>> The special handling of the object file containing the header data as
> >>> the first object file passed to the linker command line can also be
> >>> removed.
> >>>
> >>> While there also remove the special handling of efi/ on x86. There's
> >>> no need for the resulting object file to be passed in any special
> >>> order to the linker.
> >>>
> >>> Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> >>
> >> Looks good to me, but I have one question before feeling ready to
> >> offer R-b:
> >>
> >>> @@ -86,8 +84,13 @@ SECTIONS
> >>>         *(.text.kexec)          /* Page aligned in the object file. */
> >>>         kexec_reloc_end = .;
> >>>  
> >>> -       *(.text.cold)
> >>> -       *(.text.unlikely)
> >>> +       *(.text.cold .text.cold.*)
> >>> +       *(.text.unlikely .text.*_unlikely .text.unlikely.*)
> >>
> >> What generates .text.*_unlikely? And if anything really does, why
> >> would .text.cold not have a similar equivalent?
> > 
> > That matches what I saw in the default linker script from my version
> > of GNU ld:
> > 
> >     *(.text.unlikely .text.*_unlikely .text.unlikely.*)
> > 
> > I really don't know what could generate .text.*_unlikely, but since
> > it's part of the default linker script I assumed it was better to just
> > add it.
> 
> I've checked - gcc up to 4.5.x would generate .text.*_unlikely; from
> 4.6.x. onwards it would be .text.unlikely.*.
> 
> As to the dissimilarity with .text.cold: I wonder why we have that in
> the first place. It matches our __cold attribute, just that we don't
> use that anywhere afaics.
> 
> In any event:
> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
> albeit preferably with .text.cold.* dropped again.

Would you mind dropping the .text.cold.* at commit? Otherwise I can
resend.

Thanks, Roger.