Re: [PULL 17/20] configure: Poison all current target-specific #defines

[Philippe Mathieu-Daudé]

On 5/14/21 2:15 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.
> 
> Message-Id: <20210414112004.943383-5-thuth@redhat.com>
> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>  Makefile              | 2 +-
>  configure             | 7 +++++++
>  include/exec/poison.h | 2 ++
>  3 files changed, 10 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) $(NINJAFLAGS) -t clean -g || 
> :
> -     rm -f config-host.mak config-host.h*
> +     rm -f config-host.mak config-host.h* config-poison.h
>       rm -f tests/tcg/config-*.mak
>       rm -f config-all-disas.mak config.status
>       rm -f roms/seabios/config.mak roms/vgabios/config.mak
> diff --git a/configure b/configure
> index f05ca143b3..0e4233fd8a 100755
> --- a/configure
> +++ b/configure
> @@ -6473,6 +6473,13 @@ if test -n "${deprecated_features}"; then
>      echo "  features: ${deprecated_features}"
>  fi
>  
> +# Create list of config switches that should be poisoned in common code...
> +# but 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

In my --disable-system builds I'm getting:

sed: can't read *-config-devices.h: No such file or directory


>  # Save the configure command line for later reuse.
>  cat <<EOD >config.status
>  #!/bin/sh
> diff --git a/include/exec/poison.h b/include/exec/poison.h
> index a527def5f0..7ad4ad18e8 100644
> --- a/include/exec/poison.h
> +++ b/include/exec/poison.h
> @@ -4,6 +4,8 @@
>  #ifndef HW_POISON_H
>  #define HW_POISON_H
>  
> +#include "config-poison.h"
> +
>  #pragma GCC poison TARGET_I386
>  #pragma GCC poison TARGET_X86_64
>  #pragma GCC poison TARGET_AARCH64
>