Monocultures are bad [Was: Re: [PATCH] build: Extract trusted-firmware-a.mk]

[Andre Heider]

On 12/10/2020 12:21, Petr Štetiar wrote:
> Hauke Mehrtens <hauke at hauke-m.de> [2020-10-11 20:41:21]:
> 
> Hi,
> 
>   (I've expressed this already in my initial review[1] which was not addressed
>    and pushed anyway.)
> 
>> +TFA_MAKE_FLAGS += \
>> +		CROSS_CM3=$(STAGING_DIR_IMAGE)/$(LINARO_NAME)-$(LINARO_RELEASE).$(LINARO_VERSION)/bin/arm-linux-gnueabi- \
> 
> AFAIU this is Linux only toolchain, so we should either stop pretending, that
> we support usage of FreeBSD/macOS as the build host OS or fix this for good.

As with other boards, we need a secondary cross compiler for a cortex m3 
cpu here. Yes, currently a linux binary toolchain is downloaded. It's 
not optimal, and I'm not a fan of this solution either. But that's 
already used, this patch doesn't change that fact.

Building a firmware for these boards is a total clusterfuck. So one goal 
of all the espressobin PRs has been for openwrt to provide binary 
firmware files. With that in mind I see two options:

1) Error out on !Linux build hosts. Maybe that's good enough, because we 
mainly want it to work on buildbot
2) build a cm3 cross compiler

I'd go for 2), but the main question is if that's acceptable, because 
every buildslave would need to build it. We just need a bare metal 
toolchain though, so just binutils and gcc, no libc, g++ and whatnot. 
That's actually not as much as it sounds. And if we had that, the sunxi 
and rockchip atf package could use it too instead of downloading 
binaries (yay).

> BTW I'm wondering why this can't be handled in the same way
> arm-trusted-firmware-rockchip is?

For sunxi and rockchip, you start with an atf build, and then pass the 
filename of the resulting binary to the u-boot build system.

For A3700, it's the other way around. You cannot ship atf binaries 
(yuck), because atf is the last element in the build chain.

> 
> 1. https://github.com/openwrt/openwrt/pull/2521#pullrequestreview-309946728
> 
> -- ynezz
>