Re: [Qemu-devel] [PATCH for-2.7] pc-bios/optionrom: Fix OpenBSD build with better detection of linker emulation

[Brad Smith <brad@comstyle.com>]

On 08/08/16 12:11, Peter Maydell wrote:
> The various host OSes are irritatingly variable about the name
> of the linker emulation we need to pass to ld's -m option to
> build the i386 option ROMs. Instead of doing this via a
> CONFIG ifdef, check in configure whether any of the emulation
> names we know about will work and pass the right answer through
> to the makefile. If we can't find one, we fall back to not trying
> to build the option ROMs, in the same way we would for a non-x86
> host platform.
>
> This is in particular necessary to unbreak the build on OpenBSD,
> since it wants a different answer to FreeBSD and we don't have
> an existing CONFIG_ variable that distinguishes the two.

To add to this.. amd64 uses "elf_i386". Looking at i386 it uses
elf_i386_obsd and that is the only emulation supported.

So change the list of emulations to try to

elf_i386 elf_i386_fbsd elf_i386_obsd i386pe


Someone needs to take a look at what NetBSD / DragonFly are
using.

> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
> This works for Linux and for the Windows builds; I don't have any
> BSD systems to test it on. Brad and Sean, can I ask you to test this
> on OpenBSD and FreeBSD, please?
>
> (I think this is going to miss -rc2. Sorry about that; we'll
> get OpenBSD builds fixed for -rc3.)
>
>  configure                  | 12 +++++++++++-
>  pc-bios/optionrom/Makefile | 12 +-----------
>  2 files changed, 12 insertions(+), 12 deletions(-)
>
> diff --git a/configure b/configure
> index f57fcc6..7c744ad 100755
> --- a/configure
> +++ b/configure
> @@ -4699,7 +4699,16 @@ roms=
>  if test \( "$cpu" = "i386" -o "$cpu" = "x86_64" \) -a \
>          "$targetos" != "Darwin" -a "$targetos" != "SunOS" -a \
>          "$softmmu" = yes ; then
> -  roms="optionrom"
> +    # Different host OS linkers have different ideas about the name of the ELF
> +    # emulation. Linux and OpenBSD use 'elf_i386'; FreeBSD uses the _fbsd
> +    # variant; and Windows uses i386pe.
> +    for emu in elf_i386 elf_i386_fbsd i386pe; do
> +        if "$ld" -verbose 2>&1 | grep -q "^[[:space:]]*$emu[[:space:]]*$"; then
> +            ld_i386_emulation="$emu"
> +            roms="optionrom"
> +            break
> +        fi
> +    done
>  fi
>  if test "$cpu" = "ppc64" -a "$targetos" != "Darwin" ; then
>    roms="$roms spapr-rtas"
> @@ -5539,6 +5548,7 @@ fi
>  echo "LDFLAGS=$LDFLAGS" >> $config_host_mak
>  echo "LDFLAGS_NOPIE=$LDFLAGS_NOPIE" >> $config_host_mak
>  echo "LD_REL_FLAGS=$LD_REL_FLAGS" >> $config_host_mak
> +echo "LD_I386_EMULATION=$ld_i386_emulation" >> $config_host_mak
>  echo "LIBS+=$LIBS" >> $config_host_mak
>  echo "LIBS_TOOLS+=$libs_tools" >> $config_host_mak
>  echo "PTHREAD_LIB=$PTHREAD_LIB" >> $config_host_mak
> diff --git a/pc-bios/optionrom/Makefile b/pc-bios/optionrom/Makefile
> index 24e175e..5bbe233 100644
> --- a/pc-bios/optionrom/Makefile
> +++ b/pc-bios/optionrom/Makefile
> @@ -41,18 +41,8 @@ build-all: multiboot.bin linuxboot.bin linuxboot_dma.bin kvmvapic.bin
>  %.o: %.S
>  	$(call quiet-command,$(CPP) $(QEMU_INCLUDES) $(QEMU_DGFLAGS) -c -o - $< | $(AS) $(ASFLAGS) -o $@,"  AS    $(TARGET_DIR)$@")
>
> -ifdef CONFIG_WIN32
> -LD_EMULATION = i386pe
> -else
> -ifdef CONFIG_BSD
> -LD_EMULATION = elf_i386_fbsd
> -else
> -LD_EMULATION = elf_i386
> -endif
> -endif
> -
>  %.img: %.o
> -	$(call quiet-command,$(LD) $(LDFLAGS_NOPIE) -m $(LD_EMULATION) -Ttext 0 -e _start -s -o $@ $<,"  Building $(TARGET_DIR)$@")
> +	$(call quiet-command,$(LD) $(LDFLAGS_NOPIE) -m $(LD_I386_EMULATION) -Ttext 0 -e _start -s -o $@ $<,"  Building $(TARGET_DIR)$@")
>
>  %.raw: %.img
>  	$(call quiet-command,$(OBJCOPY) -O binary -j .text $< $@,"  Building $(TARGET_DIR)$@")
>