Re: [PATCH 2/3] x86/boot: Reuse code to relocate trampoline

[Frediano Ziglio <frediano.ziglio@xxxxxxxxx>]

On Mon, Oct 7, 2024 at 10:47 AM Andrew Cooper <andrew.cooper3@xxxxxxxxxx> wrote:
>
> On 07/10/2024 10:04 am, Jan Beulich wrote:
> > On 07.10.2024 10:15, Frediano Ziglio wrote:
> >> On Mon, Oct 7, 2024 at 9:07 AM Frediano Ziglio
> >> <frediano.ziglio@xxxxxxxxx> wrote:
> >>> On Mon, Oct 7, 2024 at 8:03 AM Jan Beulich <jbeulich@xxxxxxxx> wrote:
> >>>> On 05.10.2024 15:21, Andrew Cooper wrote:
> >>>>> On 05/10/2024 9:02 am, Frediano Ziglio wrote:
> >>>>>> --- a/xen/arch/x86/boot/Makefile
> >>>>>> +++ b/xen/arch/x86/boot/Makefile
> >>>>>> @@ -1,6 +1,6 @@
> >>>>>> -obj-bin-y += head.o cbundle.o
> >>>>>> +obj-bin-y += head.o cbundle.o reloc-trampoline.x64.o
> >>>>> Ah.  I think the $(obj)/%.x64.o rule you had in the previous patch wants
> >>>>> introducing here.
> >>>>>
> >>>>> That said, x64 is the one name for 64bit that we reliably don't use.
> >>>>> Also...
> >>>>>
> >>>>>> -head-bin-objs := cmdline.o reloc.o
> >>>>>> +head-bin-objs := cmdline.o reloc.o reloc-trampoline.o
> >>>>> ... head-bin-objs isn't really correct now seeing as they're not
> >>>>> binaries in head.S.  Also ...
> >>>>>
> >>>>>>  nocov-y   += $(head-bin-objs)
> >>>>>>  noubsan-y += $(head-bin-objs)
> >>>>> The no$(foo)'s needs extending to the 64bit objects too.  They're also
> >>>>> used early enough to explode.
> >>>>>
> >>>>> In Xen, 64bit objects are the norm, and it's 32bit ones which are the
> >>>>> exception, so how about we special case *.i386.o instead.  Then
> >>>>>
> >>>>> obj32 := cmdline.i386.o
> >>>>> obj32 += reloc.i386.o
> >>>>> obj32 += reloc-trampoline.i386.o
> >>>> I'd like to advocate for ix86 or i686. i386 gives a wrong impression imo.
> >>> Why not simply x86 ? We already use it.
> >>>
> >> Looking at current files, we also use (to distinguish more clearly 32
> >> and 64 bit) x86_32.
> > Either would be fine with me; as to x86 I took it that Andrew wanted to
> > express the 32-bit-ness, which x86 alone doesn't unambiguously do.
>
> On further thought, why not just foo.32.o ?
>
> That should be clear enough.
>
> ~Andrew

At this point, it starts to be more of a personal preference.
I slightly prefer x86_32 looking at file names and Makefile's macros.
Pick one.

Frediano