Re: [PATCH v2] Partially revert "build: -no-pie is no functional linker flag"

[Michael Roth]

Quoting Jessica Clarke (2021-08-05 14:25:45)
> This partially reverts commit bbd2d5a8120771ec59b86a80a1f51884e0a26e53.
> 
> This commit was misguided and broke using --disable-pie on any distro
> that enables PIE by default in their compiler driver, including Debian
> and its derivatives. Whilst -no-pie is not a linker flag, it is a
> compiler driver flag that ensures -pie is not automatically passed by it
> to the linker. Without it, all compile_prog checks will fail as any code
> built with the explicit -fno-pie will fail to link with the implicit
> default -pie due to trying to use position-dependent relocations. The
> only bug that needed fixing was LDFLAGS_NOPIE being used as a flag for
> the linker itself in pc-bios/optionrom/Makefile.
> 
> Note this does not reinstate exporting LDFLAGS_NOPIE, as it is unused,
> since the only previous use was the one that should not have existed. I
> have also updated the comment for the -fno-pie and -no-pie checks to
> reflect what they're actually needed for.
> 
> Fixes: bbd2d5a8120771ec59b86a80a1f51884e0a26e53
> Cc: Christian Ehrhardt <christian.ehrhardt@canonical.com>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: qemu-stable@nongnu.org
> Signed-off-by: Jessica Clarke <jrtc27@jrtc27.com>

Ping. --disable-pie builds are broken on Ubuntu 20.04 without this regression
fix. Looking to include it for v6.0.1/v6.1.1.

> ---
> Changes in v2:
>   * Actually include the comment change; didn't add the hunk when
>     amending...
> 
>  configure | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/configure b/configure
> index 9a79a004d7..8aecd277ed 100755
> --- a/configure
> +++ b/configure
> @@ -2246,9 +2246,11 @@ static THREAD int tls_var;
>  int main(void) { return tls_var; }
>  EOF
>  
> -# Check we support --no-pie first; we will need this for building ROMs.
> +# Check we support -fno-pie and -no-pie first; we will need the former for
> +# building ROMs, and both for everything if --disable-pie is passed.
>  if compile_prog "-Werror -fno-pie" "-no-pie"; then
>    CFLAGS_NOPIE="-fno-pie"
> +  LDFLAGS_NOPIE="-no-pie"
>  fi
>  
>  if test "$static" = "yes"; then
> @@ -2264,6 +2266,7 @@ if test "$static" = "yes"; then
>    fi
>  elif test "$pie" = "no"; then
>    CONFIGURE_CFLAGS="$CFLAGS_NOPIE $CONFIGURE_CFLAGS"
> +  CONFIGURE_LDFLAGS="$LDFLAGS_NOPIE $CONFIGURE_LDFLAGS"
>  elif compile_prog "-Werror -fPIE -DPIE" "-pie"; then
>    CONFIGURE_CFLAGS="-fPIE -DPIE $CONFIGURE_CFLAGS"
>    CONFIGURE_LDFLAGS="-pie $CONFIGURE_LDFLAGS"
> -- 
> 2.17.1
> 
>