[U-Boot] [PATCH] kbuild: move ARCH, CPU, etc. to top Makefile to fix random build error

[Stephen Warren <swarren@wwwdotorg.org>]

On 03/31/2015 06:02 AM, Masahiro Yamada wrote:
> Since the Kconfig conversion, some developers have reported that
> Kbuild sometimes fails completely at random.  According to the error
> reports, it seems to occur for any target board, but only on very
> fast computers.
>
> The log message for the fail case is like this:
>
>    make[1]: *** No rule to make target `../arch//cpu/u-boot.lds',
>    needed by `u-boot.lds'.  Stop.
>
> It looks like the top config.mk has not been included for *some*
> reason, and $(ARCH) has been left blank.
>
> I suspect "autoconf_is_current" is not working in some situation.
>
> This commit moves the definition of ARCH, CPU, SOC, etc. to the
> top Makefile, so they are surely set.

This doesn't solve the issue for me, although it improves the chance of 
success and changes the error I get.

With and without this patch, I ran:

CROSS_COMPILE=arm-linux-gnueabi- ./MAKEALL rpi_2

... until whichever of success/fail had the fewest "hits" had at least 5 
"hits".

Without this patch, the build failed 6 out of 11 runs with:

======================================================================
boards.cfg is up to date. Nothing to do.
Building rpi_2 board...
arm-linux-gnueabi-size: './u-boot': No such file
make: *** No rule to make target `arch//cpu/u-boot.lds', needed by 
`u-boot.lds'.  Stop.
make: *** Waiting for unfinished jobs....

--------------------- SUMMARY ----------------------------
Boards compiled: 1
Boards with warnings but no errors: 1 ( rpi_2 )
----------------------------------------------------------
======================================================================

With this patch, the build failed 5 out of 28 runs with:

======================================================================
boards.cfg is up to date. Nothing to do.
Building rpi_2 board...
arm-linux-gnueabi-size: './u-boot': No such file
make: *** [prepare1] Error 1
   Your architecture does not support generic board.
   Please undefine CONFIG_SYS_GENERIC_BOARD in your board config file.
make: *** [prepare1] Error 1

--------------------- SUMMARY ----------------------------
Boards compiled: 1
Boards with errors: 1 ( rpi_2 )
----------------------------------------------------------
======================================================================

This feels more like a missing dependency or similar timing issue than 
an issue with the order of variable setup in the makefile.

I tried to repro this on a couple of VM services (Linode 8192, and EC2 
c3.2xlarge) with the idea you could debug on those systems, but could 
not repro on those. Unfortunately the machine I have which repros the 
issue is on my work network, so I can't give you access.

One comment on the patch below:

> diff --git a/Makefile b/Makefile

> +ARCH		= $(CONFIG_SYS_ARCH:"%"=%)
> +CPU		= $(CONFIG_SYS_CPU:"%"=%)
> +SOC		= $(CONFIG_SYS_SOC:"%"=%)
> +VENDOR		= $(CONFIG_SYS_VENDOR:"%"=%)
> +BOARD		= $(CONFIG_SYS_BOARD:"%"=%)
> +CPUDIR		= arch/$(ARCH)/cpu$(if $(CPU),/$(CPU),)
> +BOARDDIR	= $(if $(BOARD),$(if $(VENDOR),$(VENDOR)/)$(BOARD))

> diff --git a/scripts/Makefile.autoconf b/scripts/Makefile.autoconf

> +ARCH		= $(CONFIG_SYS_ARCH:"%"=%)
> +CPU		= $(CONFIG_SYS_CPU:"%"=%)
> +SOC		= $(CONFIG_SYS_SOC:"%"=%)
> +VENDOR		= $(CONFIG_SYS_VENDOR:"%"=%)
> +BOARD		= $(CONFIG_SYS_BOARD:"%"=%)
> +CPUDIR		= arch/$(ARCH)/cpu$(if $(CPU),/$(CPU),)
> +BOARDDIR	= $(if $(BOARD),$(if $(VENDOR),$(VENDOR)))

Duplicating that doesn't seem like a good idea. Could it at least be 
included from a shared foo.mk file?