[PATCH 1/1] sandbox: allow cross-compiling sandbox

[AKASHI Takahiro <takahiro.akashi@linaro.org>]

On Mon, Feb 08, 2021 at 09:29:43PM -0700, Simon Glass wrote:
> Hi Heinrich,
> 
> On Mon, 8 Feb 2021 at 15:06, Heinrich Schuchardt <xypron.glpk@gmx.de> wrote:
> >
> > UEFI test files like helloworld.efi require an architecture specific
> > PE-COFF header.
> 
> architecture-specific
> 
> >
> > For non-sandbox the PE-COFF header is chosen by the target architecture.
> > For the sandbox we use the host architecture. This is not helpful for cross
> > compiling. Allow specifying the target architecture of the sandbox via
> > environment variable MK_ARCH, e.g.
> 
> What exactly is the target arch? Is the the one that sandbox is
> running on, or something else?
> 
> >
> >     make sandbox_defconfig NO_SDL=1
> >     CROSS_COMPILE=aarch64-linux-gnu- NO_SDL=1 MK_ARCH=aarch64 make
> >
> > Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
> > ---
> >  Makefile             |  2 +-
> >  doc/arch/sandbox.rst | 14 ++++++++++++++
> >  2 files changed, 15 insertions(+), 1 deletion(-)
> >
> > diff --git a/Makefile b/Makefile
> > index 23dd11f723..286e5148ae 100644
> > --- a/Makefile
> > +++ b/Makefile
> > @@ -19,7 +19,7 @@ MAKEFLAGS += -rR --include-dir=$(CURDIR)
> >
> >  # Determine host architecture
> >  include include/host_arch.h
> > -MK_ARCH="${shell uname -m}"
> > +MK_ARCH?="${shell uname -m}"
> >  unexport HOST_ARCH
> >  ifeq ("x86_64", $(MK_ARCH))
> >    export HOST_ARCH=$(HOST_ARCH_X86_64)
> > diff --git a/doc/arch/sandbox.rst b/doc/arch/sandbox.rst
> > index 60ee1e0741..0dd9edc8cb 100644
> > --- a/doc/arch/sandbox.rst
> > +++ b/doc/arch/sandbox.rst
> > @@ -33,6 +33,20 @@ integers can only be built on 64-bit hosts.
> >
> >  Note that standalone/API support is not available at present.
> >
> > +Cross compiling
> > +---------------
> > +
> > +When cross compiling the U-Boot sandbox with CONFIG_EFI_LOADER=y the target
> > +architecture must be specified using the MK_ARCH environment variable using one
> > +of the values aarch64, armv7l, i386, riscv32, riscv64, x86_64, e.g.
> 
> OK, but what is the target architecture? I'm just not sure from your
> comments what this actually means.

I'm not quite sure if it is very useful to be able to cross-compile
the sandbox application. But any way, it is not very convenient
to always enforce users to explicitly specify "target" architecture.
How about trying the following first?
$(CC) -v | grep "Target: " | sed -e 's/-*$//'

It will give us a hint about the architecture.
("--print-multiarch" shows a similar triple, but this option won't
work for some pre-built gcc, like aarch64 gcc from Arm.)

> Does MK mean make?

I prefer another name for clarity.

-Takahiro Akashi

> 
> > +
> > +.. code-block:: bash
> > +
> > +    NO_SDL=1 make sandbox_defconfig
> > +    CROSS_COMPILE=aarch64-linux-gnu- MK_ARCH=aarch64 NO_SDL=1 make
> > +
> > +NO_SDL=1 was chosen in the example to remove the dependency on the SDL library.
> > +The graphical console will not be available.
> >
> >  Prerequisites
> >  -------------
> > --
> > 2.30.0
> >
> 
> Regards,
> Simon