[PATCH v2 2/2] arm64: efi: add vmlinux debug link to the Image binary

[Mark Rutland]

On Wed, Jan 25, 2017 at 12:00:44PM +0000, Ard Biesheuvel wrote:
> On 25 January 2017 at 11:53, Mark Rutland <mark.rutland at arm.com> wrote:
> > On Wed, Jan 25, 2017 at 10:39:19AM +0000, Ard Biesheuvel wrote:
> >> When building with debugging symbols, take the absolute path to the
> >> vmlinux binary and add it to the special PE/COFF debug table entry.
> >>
> >> These entries are used internally by EDK2 based* debug builds of UEFI
> >> to populate the DebugImageInfo table, which can be used by debuggers
> >> as well as by the OS itself to retrieve information about all loaded
> >> PE/COFF executables. This is highly useful for source level debugging
> >> of the UEFI stub.
> >
> > Does that mean EFI_IMAGE_DEBUG_DIRECTORY_ENTRY and friends are
> > EDK2-specific?
> >
> > Or just that the way EDK2 happens to use those is EDK2-specific?
> 
> Those values are defined by the PE/COFF spec, and I assume that a
> CodeView type entry in the debug table usually contains a NUL
> terminated string as well, given that the EDK2 crowd is very
> Wintel-heavy.

So we don't actually have a definition of the format of a CodeView
entry, and we're guessing?

That does feel a little scary, especially given the fields are named
"Unknown". :(

> The significance of mentioning EDK2 here was that I thought that the
> DebugImageInfo table was a PI construct rather than something
> described in the UEFI spec. But looking more carefully, it seems that
> this table is in fact a UEFI construct, so I should probably drop this
> mention from the commit log

That would probably be for the best, yes.

Thanks,
Mark.