Re: [Xen-devel] [PATCH v14 2/9] efi: build xen.gz with EFI code

[Daniel Kiper <daniel.kiper@xxxxxxxxxx>]

On Thu, Feb 02, 2017 at 11:01:12PM +0100, Daniel Kiper wrote:
> Build xen.gz with EFI code. We need this to support multiboot2
> protocol on EFI platforms.
>
> If we wish to load non-ELF file using multiboot (v1) or multiboot2 then
> it must contain "linear" (or "flat") representation of code and data.
> This is requirement of both boot protocols. Currently, PE file contains
> many sections which are not "linear" (one after another without any holes)
> or even do not have representation in a file (e.g. BSS). From EFI point
> of view everything is OK and works. However, this file layout cannot be
> properly interpreted by multiboot protocols family. In theory there is
> a chance that we could build proper PE file (from multiboot protocols POV)
> using current build system. However, it means that xen.efi further diverge
> from Xen ELF file (in terms of contents and build method). On the other
> hand ELF has all needed properties. So, it means that this is good starting
> point for further development. Additionally, I think that this is also good
> starting point for further xen.efi code and build optimizations. It looks
> that there is a chance that finally we can generate xen.efi directly from
> Xen ELF using just simple objcopy or other tool. This way we will have one
> Xen binary which can be loaded by three boot protocols: EFI native loader,
> multiboot (v1) and multiboot2.
>
> Signed-off-by: Daniel Kiper <daniel.kiper@xxxxxxxxxx>
> Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
> Reviewed-by: Doug Goldstein <cardoe@xxxxxxxxxx>
> ---
> v14 - suggestions/fixes:
>     - at least GNU Make 4.1 does not build efi/buildid.o if nothing
>       depends on it; so, add "boot.init.o: buildid.o" dependency to
>       force efi/buildid.o on some versions of make; I hope that this
>       small change does not invalidate Acked-by/Reviewed-by; however,
>       I am dropping Tested-by
>       (discovered by Konrad Rzeszutek Wilk and Marcos Matsunaga).

Diff as Doug asked:

diff --git a/xen/arch/x86/efi/Makefile b/xen/arch/x86/efi/Makefile
index 442f3fc..3edff1c 100644
--- a/xen/arch/x86/efi/Makefile
+++ b/xen/arch/x86/efi/Makefile
@@ -8,6 +8,8 @@ efi := $(if $(efi),$(shell rm disabled)y)
 %.o: %.ihex
        $(OBJCOPY) -I ihex -O binary $< $@

+boot.init.o: buildid.o
+
 obj-y := stub.o
 obj-$(efi) := boot.init.o compat.o relocs-dummy.o runtime.o
 extra-$(efi) += buildid.o

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