Re: [PATCH for-6.1 4/4] configure: Poison all current target-specific #defines

[Philippe Mathieu-Daudé]

+Richard/Claudio

On 4/14/21 1:20 PM, Thomas Huth wrote:
> We are generating a lot of target-specific defines in the *-config-devices.h
> and *-config-target.h files. Using them in common code is wrong and leads
> to very subtle bugs since a "#ifdef CONFIG_SOMETHING" is not working there
> as expected. To avoid these issues, we are already poisoning many of the
> macros in include/exec/poison.h - but it's cumbersome to maintain this
> list manually. Thus let's generate an additional list of poisoned macros
> automatically from the current config switches - this should give us a
> much better test coverage via the different CI configurations.
> 
> Note that CONFIG_TCG (which is also defined in config-host.h) and
> CONFIG_USER_ONLY are special, so we have to filter these out.

I know if we poison CONFIG_TCG, almost nothing build, but I fail to
see how it is different from the other accelerators. I suppose in the
future (maybe with Claudio's effort) we could have it not special.

> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>  Makefile              | 2 +-
>  configure             | 5 +++++
>  include/exec/poison.h | 2 ++
>  3 files changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/Makefile b/Makefile
> index bcbbec71a1..4cab10a2a4 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -213,7 +213,7 @@ qemu-%.tar.bz2:
>  
>  distclean: clean
>       -$(quiet-@)test -f build.ninja && $(NINJA) $(NINJAFLAGS) -t clean -g || 
> :
> -     rm -f config-host.mak config-host.h*
> +     rm -f config-host.mak config-host.h* config-poison.h
>       rm -f tests/tcg/config-*.mak
>       rm -f config-all-disas.mak config.status
>       rm -f roms/seabios/config.mak roms/vgabios/config.mak
> diff --git a/configure b/configure
> index 4f374b4889..a0f0601e7e 100755
> --- a/configure
> +++ b/configure
> @@ -6440,6 +6440,11 @@ if test -n "${deprecated_features}"; then
>      echo "  features: ${deprecated_features}"
>  fi
>  

Maybe a one line comment (but since it is obvious, I don't mind):

   # Filter out CONFIG_TCG and CONFIG_USER_ONLY which are special

> +sed -n -e '/CONFIG_TCG/d' -e '/CONFIG_USER_ONLY/d' \
> +    -e '/^#define / { s///; s/ .*//; s/^/#pragma GCC poison /p; }' \
> +    *-config-devices.h *-config-target.h | \
> +    sort -u > config-poison.h
> +

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>