Re: [Xen-devel] [PATCH v15 05/10] x86: add multiboot2 protocol support for EFI platforms

[Daniel Kiper <daniel.kiper@xxxxxxxxxx>]

On Wed, Feb 15, 2017 at 03:22:02AM -0700, Jan Beulich wrote:
> >>> On 14.02.17 at 19:38, <daniel.kiper@xxxxxxxxxx> wrote:
> > --- a/xen/arch/x86/boot/head.S
> > +++ b/xen/arch/x86/boot/head.S
> > @@ -394,10 +394,18 @@ __start:
> >
> >          /* EFI IA-32 platforms are not supported. */
> >          cmpl    $MULTIBOOT2_TAG_TYPE_EFI32,MB2_tag_type(%ecx)
> > +        /*
> > +         * Here we should zap vga_text_buffer. However, we can disable
> > +         * VGA updates in simpler and more reliable way later.
> > +         */
> >          je      .Lmb2_efi_ia_32
> >
> >          /* Bootloader shutdown EFI x64 boot services. */
> >          cmpl    $MULTIBOOT2_TAG_TYPE_EFI64,MB2_tag_type(%ecx)
> > +        /*
> > +         * Here we should zap vga_text_buffer. However, we can disable
> > +         * VGA updates in simpler and more reliable way later.
> > +         */
> >          je      .Lmb2_no_bs
>
> I'm afraid I don't view these comments as helpful in understanding
> the whole situation. That's partly because I don't follow both the
> "simpler" and "more reliable" parts (using just the information here,

OK, I will clarify it.

> i.e. leaving aside what you've given as explanation earlier, albeit I
> don't think that was fully clarifying things either), and partly
> because I continue to think that the explanation should go where
> the labels are (which is what I had meant to suggest with my
> comment placement in reply to v14). Nor does the adjustment

OK.

> above help (me) understand the correctness of the dual use of
> .Lmb2_no_bs.

What do you mean by "dual use of .Lmb2_no_bs."? I would like to be sure.

By the way, what about second half of the patch series? Does it make sense or
a little or is it total crap? Could you say something? You have not commented
it for a few releases, so, there is a chance that it is OK. However, opposite
is also possible. So, if you wish to fix something please say it now than later.
Then I will have more time to do the work.

Daniel

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