FS#4073 - make kernel_menuconfig fails at m4 1.4.18 in Ubuntu 21.10 because of SIGSTKSZ

[openwrt-bot]

dreamlayers:

I'm attempting to build openwrt 21.02 from git for a Buffalo WZR-600DHP on x86_64 Ubuntu 21.10. make kernel_menuconfig failed, and after running it with increased verbosity I see:

gcc  -I.   -I/home/bgjenero/gitapps/openwrt/staging_dir/host/include   -O2 -I/home/bgjenero/gitapps/openwrt/staging_dir/host/include  -MT c-stack.o -MD -MP -MF $depbase.Tpo -c -o c-stack.o c-stack.c &&\
mv -f $depbase.Tpo $depbase.Po
In file included from /usr/include/signal.h:328,
                 from ./signal.h:52,
                 from c-stack.c:49:
c-stack.c:55:26: error: missing binary operator before token "("
   55 | #elif HAVE_LIBSIGSEGV && SIGSTKSZ < 16384
      |                          ^~~~~~~~

That's a failure building m4 1.4.18. It is discussed at https://lists.gnu.org/archive/html/bug-m4/2021-03/msg00000.html

The problem is that m4 is expecting SIGSTKSZ to be a compile time constant, but instead in
/usr/include/x86_64-linux-gnu/bits/sigstksz.h it is: # define SIGSTKSZ sysconf (_SC_SIGSTKSZ)

The m4 package in Ubuntu 21.10 is actually the same version, and the source package has a patch for this in https://launchpad.net/ubuntu/+archive/primary/+sourcefiles/m4/1.4.18-5ubuntu1/m4_1.4.18-5ubuntu1.debian.tar.xz at /debian/patches/04-fix-sigstksz.patch. I am attaching that patch here.

[openwrt-bot]

yarrick:

I get the same failure (using Fedora 35)

Ah, I get this only because I used a branch based on older code. master already has newer m4

[detly]

I'm hitting this trying to compile older OpenWRT versions (18.06) on Ubuntu 21.10. Is there a simple workaround?

[NumberOneGit]

I think the workaround is to patch c-stack.c with the above patchfile.

[detly]

Ah, I wasn't sure whether it was the host or OpenWRT that needed patching. I actually did something else and backported the current version of m4.