On 6/21/22 16:55, Richard Henderson wrote:
On 6/21/22 00:51, Paolo Bonzini wrote:
diff --git a/pc-bios/optionrom/Makefile b/pc-bios/optionrom/Makefile
index ea89ce9d59..e90ca2e1c6 100644
--- a/pc-bios/optionrom/Makefile
+++ b/pc-bios/optionrom/Makefile
@@ -11,7 +11,7 @@ CFLAGS = -O2 -g
quiet-command = $(if $(V),$1,$(if $(2),@printf " %-7s %s\n" $2 $3
&& $1, @$1))
cc-option = $(if $(shell $(CC) $1 -c -o /dev/null -xc /dev/null
>/dev/null 2>&1 && echo OK), $1, $2)
-override CFLAGS += -march=i486 -Wall -m16
+override CFLAGS += -march=i486 -Wall $(EXTRA_CFLAGS) -m16
Hmm. I'm not sure about this. Given that EXTRA_CFLAGS is going to be
e.g. -m32 or empty, being immediately overwritten to -m16, I don't quite
see the point.
I added it mostly for consistency with the other pc-bios subdirectories,
and because it can also be overridden with --cross-cflags-i386 though.
Even for the default -m32, however, there would be a reason to have
$(EXTRA_FLAGS) in there. I have played with removing the direct use of
"ld -m" in the build of pc-bios/optionrom, and stumbled on a weird GCC
configuration issue. The problem is that some hosts pick the right
linker emulation when given -m16, but others don't:
$ gcc -dumpspecs
...
*link:
... %{m16|m32|mx32:;:-m elf_x86_64} %{m16|m32:-m elf_i386}
# x86_64-w64-mingw32-gcc
...
*link:
%{!m32:-m i386pep} %{m32:-m i386pe} ...
The error is in GCC's gcc/config/i386/mingw-w64.h, which provides a
MULTILIB_DEFAULTS #define but does not rely on it:
#undef SPEC_32
#undef SPEC_64
#if TARGET_64BIT_DEFAULT
#define SPEC_32 "m32" // should be m16|m32
#define SPEC_64 "!m32" // should be m64
#else
#define SPEC_32 "!m64" // should be m16|m32
#define SPEC_64 "m64"
#endif
So you need -m32 -m16 on 64-bit hosts! For the "working" specs the -m16
would override -m32, while on the broken ones -m32 is for the linker and
-m16 is for the compiler.
Paolo
