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  •   gcc-10 linker failure: "multiple definition of...".

    syslinux-6.04_pre1 fails to build on gcc-10 due to -fno-common change; gcc-10 (and above) flipped a default, from -fcommon to -fno-common.

    gcc-10 will reject multiple definitions of global variables. Possible/potential workaround: add/append -fcommon to CFLAGS. Ideally, the code would need a few 'extern' additions and maybe moving variable definitions.

  •   undefined reference to `strlen'. Possibly related to (the link to) libc and/or to GCC-10+ optimizer. Solution: provide missing strlen() implementation in dos/string.h.
  •   Prevent-pow-optimization when using gcc 8.2+.
  •   internal error - lzo_init() failed! (inconsistent/sporadic error).

    Syslinux fails to build due to aliasing bugs in lzo. Add -fno-strict-aliasing to lzo/Makefile.

  •   Fix broken efi binaries with binutils 2.31+.

    "Binutils >= 2.31 writes two PT_LOAD segments by default. This is not supported by the wrapper.c script used to convert the shared object into an elf binary."

  •   If getting "Not enough room for program headers", try adding '--no-dynamic-linker' to the linker command line(s). Seen with binutils 2.27+. There might be other / better solutions / work-around methods.

    Note: 6.04-pre1+ should not be affected by this issue.

    Feedback is appreciated.

  •  When building with glibc 2.23+, the "major", "minor" and "makedev" functions are defined in "sys/sysmacros.h". The patch "extlinux: pull in sys/sysmacros.h for major/minor/makedev", applied to Syslinux during 2016Apr, should help. Please note that not only Syslinux is affected by this change in glibc.

 Patches already included in Syslinux 6.04-pre1 (released 2016Mar):

Testing Syslinux 6.04-pre1 (or later) is recommended.


  • NASM 2.11.06 has a bug which prevents Syslinux from building correctly. Use other version of NASM (e.g. 2.11.05, 2.11.08+, among others).
  • binutils 2.26, as originally released upstream, has a bug preventing Syslinux from building correctly. The bug in bintuils 2.26 was resolved in a later commit.
  • "error: impossible constraint in asm". When gcc5+ is configured with --enable-default-pie, in some cases there might be a need to use custom flags in some makefile(s), similar to either "CFLAGS += -fno-pie" or "CFLAGS := -fno-pie". Examples:

See also