Re: [Xen-devel] [PATCH v2 5/6] x86/boot: Copy 16-bit boot variables back up to Xen image

[Jan Beulich <jbeulich@xxxxxxxx>]

On 19.08.2019 17:25, David Woodhouse wrote:
> On Mon, 2019-08-12 at 12:24 +0200, Jan Beulich wrote:
> > On 09.08.2019 17:02, David Woodhouse wrote:
> > > @@ -227,7 +231,7 @@ start64:
> > >           .word   0
> > >   idt_48: .word   0, 0, 0 # base = limit = 0
> > >           .word   0
> > > -gdt_48: .word   6*8-1
> > > +gdt_48: .word   7*8-1
> > >           .long   tramp32sym_rel(trampoline_gdt,4)
> > You don't grow trampoline_gdt here, so I think this change is
> > wrong. And if a change was needed at all (perhaps in the next
> > patch), then I think it would be better to replace the use of
> > literal numbers, using the difference of two labels instead
> > (the "end" lable preferably being a .L-prefixed one).
> I don't grow it but... count it ☺.
>
> I do start using sym_fs() here in places that it wasn't before, so the
> incorrect size started to *matter* because the BOOT_FS selector wasn't
> included in the limit.
Oh, I see - a (latent) bug introduced by b28044226e. Should perhaps
be a separate patch to fix this then (by, as suggested, using an
"end" label rather than hard coded numbers).

Jan

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