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

[Heinrich Schuchardt]

On 09.02.21 12:31, AKASHI Takahiro wrote:
> On Tue, Feb 09, 2021 at 07:40:23AM +0100, Heinrich Schuchardt wrote:
>> Am 9. Februar 2021 06:30:31 MEZ schrieb AKASHI Takahiro <takahiro.akashi at 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 at 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 at 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
>>
>> Building the sandbox on ARMv7 is broken due to patch introduced in 2020. We get loads of warnings when building for 32bit.
>
> Are you using "cross-compiling" sandbox on armv7 machine?
> For what target architecture?

Compiling sandbox_defconfig without cross-compiling fails on ARMv7.

Best regards

Heinrich

>
>> We should integrate building the sandbox for different architectures into Gitlab CI.
>>
>>> 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.)
>>
>> Did you check clang?
>
> I don't know, but we must specify "--target" option explicitly
> in clang case, and according to U-Boot's Makefile, it will be uniquely
> determined from "CROSS_COMPILE".
>
> -Takahiro Akashi
>
>> Is the output format specified? Will this be stable for compiler versions to come? Given the --print-multiarch failure probably not.
>>
>> When compiling Linux you also have to supply CROSS_COMPILER and ARCH.
>>
>> For me it is anyway a Gitlab CI thing. Nothing a user would typically use.
>>
>> Best regards
>>
>> Heinrich
>>
>>
>>>
>>>> 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
>>