Re: [Xen-devel] [PATCH v2] multiboot2: clarify usage of the address tag

[Daniel Kiper <daniel.kiper@xxxxxxxxxx>]

On Fri, Jun 08, 2018 at 12:08:22PM +0200, Roger Pau Monné wrote:
> On Fri, Jun 08, 2018 at 11:35:52AM +0200, Daniel Kiper wrote:
> > On Thu, Jun 07, 2018 at 05:59:06PM +0200, Roger Pau Monne wrote:
> > > Add a note to spell out that if the address tag is not present the
> > > file should be loaded using the elf header.
> > >
> > > Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> > > ---
> > > Cc: Daniel Kiper <daniel.kiper@xxxxxxxxxx>
> > > Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx
> > > ---
> > > Changes since v1:
> > >  - s/elf/@sc{elf}/
> > >  - s/Multiboot/Multiboot2/
> > > ---
> > >  doc/multiboot.texi | 6 ++++++
> > >  1 file changed, 6 insertions(+)
> > >
> > > diff --git a/doc/multiboot.texi b/doc/multiboot.texi
> > > index 2e2d7e74a..3c797787c 100644
> > > --- a/doc/multiboot.texi
> > > +++ b/doc/multiboot.texi
> > > @@ -509,6 +509,12 @@ assumes that no bss segment is present.
> > >
> > >  @end table
> > >
> > > +Note: This information does not need to be provided if the kernel image
> > > +is in @sc{elf} format, but it must be provided if the image is in a.out
> > > +format or in some other format. Compliant boot loaders must be able to
> > > +load images that are either in @sc{elf} format or contain the address
> > > +tag embedded in the Multiboot2 header.
> > > +
> >
> > Now it is better. However, there is a lack of information that this tag
> > should be preferred over the relevant data provided in the ELF header if
> > both are available in the image. This have to be clear like it is in
> > Multiboot spec.
>
> Would you be OK with adding the following sentence at the end:
>
> "When the address tag is present it must be used in order to load the
> image, regardless of whether an @sc{elf} header is also present."

I would put this as a second sentence in note, just after "... some
other format." However, then probably last sentence should be rephrased
a bit.

Daniel

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