[BUG] PCem V15 does not compile with GCC >= 10.x

[ConiKost]

Starting with GCC >= 10.x, -fno-common is used instead of -fcommon. Compilation of PCem V15 fails.

Following output is an example, since it affects more places.
See full log: https://pastebin.com/D1diRPJY

Code: Select all

usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/../../../../x86_64-pc-linux-gnu/bin/ld: pcem-386_common.o:(.bss+0x750): multiple definition of `cpu_state'; pcem-386.o:(.bss+0x690): first defined here
/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/../../../../x86_64-pc-linux-gnu/bin/ld: pcem-386_common.o:(.bss+0xd0): multiple definition of `bios_high_mapping'; pcem-386.o:(.bss+0x0): first defined here
/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/../../../../x86_64-pc-linux-gnu/bin/ld: pcem-386_common.o:(.bss+0x410): multiple definition of `bios_mapping'; pcem-386.o:(.bss+0x340): first defined here
/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/../../../../x86_64-pc-linux-gnu/bin/ld: pcem-386_common.o:(.bss+0x8f0): multiple definition of `hdc'; pcem-386.o:(.bss+0x830): first defined here
/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/../../../../x86_64-pc-linux-gnu/bin/ld: pcem-386_common.o:(.bss+0x998): multiple definition of `pic2'; pcem-386.o:(.bss+0x8d8): first defined here
/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/../../../../x86_64-pc-linux-gnu/bin/ld: pcem-386_common.o:(.bss+0x9b0): multiple definition of `pic'; pcem-386.o:(.bss+0x8f0): first defined here
/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/../../../../x86_64-pc-linux-gnu/bin/ld: pcem-386_common.o:(.bss+0x9c8): multiple definition of `ppi'; pcem-386.o:(.bss+0x908): first defined here
/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/../../../../x86_64-pc-linux-gnu/bin/ld: pcem-386_common.o:(.bss+0x9d0): multiple definition of `ram'; pcem-386.o:(.bss+0x910): first defined here
/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/../../../../x86_64-pc-linux-gnu/bin/ld: pcem-386_dynarec.o:(.bss+0x6c0): multiple definition of `cpu_state'; pcem-386.o:(.bss+0x690): first defined here
/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/../../../../x86_64-pc-linux-gnu/bin/ld: pcem-386_dynarec.o:(.bss+0x6b8): multiple definition of `x87_pc_off'; pcem-386.o:(.bss+0x688): first defined here
/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/../../../../x86_64-pc-linux-gnu/bin/ld: pcem-386_dynarec.o:(.bss+0x6b2): multiple definition of `x87_pc_seg'; pcem-386.o:(.bss+0x682): first defined here
/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/../../../../x86_64-pc-linux-gnu/bin/ld: pcem-386_dynarec.o:(.bss+0x6b4): multiple definition of `x87_op_off'; pcem-386.o:(.bss+0x684): first defined here
/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/../../../../x86_64-pc-linux-gnu/bin/ld: pcem-386_dynarec.o:(.bss+0x6b0): multiple definition of `x87_op_seg'; pcem-386.o:(.bss+0x680): first defined here
/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/../../../../x86_64-pc-linux-gnu/bin/ld: pcem-386_dynarec.o:(.bss+0x940): multiple definition of `ram'; pcem-386.o:(.bss+0x910): first defined here
/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/../../../../x86_64-pc-linux-gnu/bin/ld: pcem-386_dynarec.o:(.bss+0x30): multiple definition of `bios_high_mapping'; pcem-386.o:(.bss+0x0): first defined here
/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/../../../../x86_64-pc-linux-gnu/bin/ld: pcem-386_dynarec.o:(.bss+0x370): multiple definition of `bios_mapping'; pcem-386.o:(.bss+0x340): first defined here
/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/../../../../x86_64-pc-linux-gnu/bin/ld: pcem-386_dynarec.o:(.bss+0x860): multiple definition of `hdc'; pcem-386.o:(.bss+0x830): first defined here
/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/../../../../x86_64-pc-linux-gnu/bin/ld: pcem-386_dynarec.o:(.bss+0x908): multiple definition of `pic2'; pcem-386.o:(.bss+0x8d8): first defined here
/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/../../../../x86_64-pc-linux-gnu/bin/ld: pcem-386_dynarec.o:(.bss+0x920): multiple definition of `pic'; pcem-386.o:(.bss+0x8f0): first defined here
/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/../../../../x86_64-pc-linux-gnu/bin/ld: pcem-386_dynarec.o:(.bss+0x938): multiple definition of `ppi'; pcem-386.o:(.bss+0x908): first defined here
/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/../../../../x86_64-pc-linux-gnu/bin/ld: pcem-386_dynarec_ops.o:(.bss+0x690): multiple definition of `cpu_state'; pcem-386.o:(.bss+0x690): first defined here
/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/../../../../x86_64-pc-linux-gnu/bin/ld: pcem-386_dynarec_ops.o:(.bss+0x688): multiple definition of `x87_pc_off'; pcem-386.o:(.bss+0x688): first defined here
/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/../../../../x86_64-pc-linux-gnu/bin/ld: pcem-386_dynarec_ops.o:(.bss+0x682): multiple definition of `x87_pc_seg'; pcem-386.o:(.bss+0x682): first defined here
/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/../../../../x86_64-pc-linux-gnu/bin/ld: pcem-386_dynarec_ops.o:(.bss+0x684): multiple definition of `x87_op_off'; pcem-386.o:(.bss+0x684): first defined here
/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/../../../../x86_64-pc-linux-gnu/bin/ld: pcem-386_dynarec_ops.o:(.bss+0x680): multiple definition of `x87_op_seg'; pcem-386.o:(.bss+0x680): first defined here
/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/../../../../x86_64-pc-linux-gnu/bin/ld: pcem-386_dynarec_ops.o:(.bss+0x0): multiple definition of `bios_high_mapping'; pcem-386.o:(.bss+0x0): first defined here
/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/../../../../x86_64-pc-linux-gnu/bin/ld: pcem-386_dynarec_ops.o:(.bss+0x340): multiple definition of `bios_mapping'; pcem-386.o:(.bss+0x340): first defined here
/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/../../../../x86_64-pc-linux-gnu/bin/ld: pcem-386_dynarec_ops.o:(.bss+0x830): multiple definition of `hdc'; pcem-386.o:(.bss+0x830): first defined here
/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/../../../../x86_64-pc-linux-gnu/bin/ld: pcem-386_dynarec_ops.o:(.bss+0x8d8): multiple definition of `pic2'; pcem-386.o:(.bss+0x8d8): first defined here
/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/../../../../x86_64-pc-linux-gnu/bin/ld: pcem-386_dynarec_ops.o:(.bss+0x8f0): multiple definition of `pic'; pcem-386.o:(.bss+0x8f0): first defined here
/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/../../../../x86_64-pc-linux-gnu/bin/ld: pcem-386_dynarec_ops.o:(.bss+0x908): multiple definition of `ppi'; pcem-386.o:(.bss+0x908): first defined here
/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/../../../../x86_64-pc-linux-gnu/bin/ld: pcem-386_dynarec_ops.o:(.bss+0x910): multiple definition of `ram'; pcem-386.o:(.bss+0x910): first defined here

[jasaldivara]

I have the same problem, both whith PCem v15 and v16.

What's the best solution? Where should I change that flag? Or should I install an older version of GCC?

[davefiddes]

This just bit me when trying out PCem on Fedora 32 which uses gcc 10.0.1 20200430 (Red Hat 10.0.1-0.13) and will probably update to the final GCC 10.1 release shortly.

A hack fix can be achieved by adding "-fcommon" to the CFLAGS settings in configure.ac (circa line 33) and re-building the configure script by running autoconf.

Seems like the -fcommon option has existed in gcc for a long time (at least as far back as gcc 4.2.4) so should be safe to add in to the default CFLAGS.

[JosepMa]

https://wiki.gentoo.org/wiki/Gcc_10_porting_notes/fno_common

It seems it could be complicated to rearrange the code in some places .

Basically, ".h" files should not have variable instantiations ( like, for example bios_high_mapping in mem.h ).
Instead, they should be defined on one .c file, and use the "extern x" keyword on .h files that would need to refer to it.

[SarahWalker]

Added -fcommon in commit 1f63723. I should probably actually fix the issue at some point...