Re: [PATCH-for-5.0] roms/edk2-funcs: Force armhf toolchain prefix on Debian

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

On 12/5/19 8:56 PM, Laszlo Ersek wrote:
> On 12/05/19 19:17, Ard Biesheuvel wrote:
>> On Thu, 5 Dec 2019 at 18:09, Philippe Mathieu-Daudé <philmd@redhat.com> wrote:
>>>
>>> The Debian (based) distributions historically provides 2 ARM
>>> toolchains, documented as [1]:
>>>
>>> * The ARM EABI (armel) port targets a range of older 32-bit ARM
>>>    devices, particularly those used in NAS hardware and a variety
>>>    of *plug computers.
>>> * The newer ARM hard-float (armhf) port supports newer, more
>>>    powerful 32-bit devices using version 7 of the ARM architecture
>>>    specification.
>>>
>>> The EDK2 documentation suggests to use the hard-float toolchain.
>>>
>>
>> We should probably fix that.
> 
> OK, I'm confused. What case are we talking about?

You answered to your questions after reviewing my v2 (see 
https://lists.gnu.org/archive/html/qemu-devel/2019-12/msg01118.html), 
still I'll reply inline for other reviewers.

> (1) Without this patch, "roms/edk2-funcs.sh" fails to select *any* cross
> compiler on Debian, and the build just croaks.

This is the correct description.

> 
> --> insist on armhf in this script?

This is what the EDK2 doc suggests in [2], but Ard says Clang default to 
armel, so we should use the GCC armel version.

> --> insist on armel in this script?

Yes, this is v2 approach:
https://lists.gnu.org/archive/html/qemu-devel/2019-12/msg01088.html

> --> pick whichever is available, because either works?

I thought about it, because Debian edk2 is packaged with 
gcc-arm-linux-gnueabihf so this is convenient to install all the 
prerequisites with 'apt build-dep edk2'. See:
https://salsa.debian.org/qemu-team/edk2/blob/debian/debian/control#L9

> 
> (2) Without this patch, "roms/edk2-funcs.sh" selects the "armel" flavor,
> and it fails to build edk2.
> 
> --> insist on armhf in this script?
> 
> (3) Without this patch, "roms/edk2-funcs.sh" selects the "armel" flavor,
> and it builds edk2 just fine -- but that's not the flavor that the edk2
> documentation suggests.
> 
> --> drop this patch, and fix the edk2 docs?

Regardless 1/2/3 we should fix the edk2 doc :)

> 
> Thanks,
> Laszlo
> 
>> tools_def.template mentions
>> arm-linux-gnueabi, and while it does not really matter in most cases,
>> if you are using Clang, you actually need the armel binutils (see
>> 41203b9ab5d48e029f24e17e9a865e54b7e1643d for details)
>>
>>
>>> Force the armhf cross toolchain prefix on Debian distributions.
>>>
>>> [1] https://www.debian.org/ports/arm/#status
>>> [2] https://github.com/tianocore/edk2-platforms/blob/master/Readme.md#if-cross-compiling
>>>
>>> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
>>> ---
>>>   roms/edk2-funcs.sh | 3 +++
>>>   1 file changed, 3 insertions(+)
>>>
>>> diff --git a/roms/edk2-funcs.sh b/roms/edk2-funcs.sh
>>> index 3f4485b201..a546aa1d11 100644
>>> --- a/roms/edk2-funcs.sh
>>> +++ b/roms/edk2-funcs.sh
>>> @@ -112,6 +112,9 @@ qemu_edk2_get_cross_prefix()
>>>        ( [ "$gcc_arch" == i686 ] && [ "$host_arch" == x86_64 ] ); then
>>>       # no cross-compiler needed
>>>       :
>>> +  elif ( [ -e /etc/debian_version ] && [ "$gcc_arch" == arm ] ); then
>>> +    # force hard-float cross-compiler on Debian
>>> +    printf 'arm-linux-gnueabihf-'
>>>     else
>>>       printf '%s-linux-gnu-\n' "$gcc_arch"
>>>     fi
>>> --
>>> 2.21.0
>>>
>>
>