qemu-irix fails to build under Alpine 3.10 (GCC 8.3) - docker

Question

Just for fun, I'm attempting to build the irixxxx's qemu-irix as a Docker image.
It builds successfuly under Debian Buster (using GCC 8 container). However, it fails to build under Alpine 3.10 (it fails only when I selected the Irix targets), with the following errors (at the make stage):
CC util/oslib-posix.o
In file included from util/oslib-posix.c:39:
/usr/include/sys/signal.h:1:2: warning: #warning redirecting incorrect #include <sys/signal.h> to <signal.h> [-Wcpp]
#warning redirecting incorrect #include <sys/signal.h> to <signal.h>
^~~~~~~
CC util/qemu-openpty.o
util/qemu-openpty.c: In function 'qemu_openpty_raw':
util/qemu-openpty.c:123:9: warning: implicit declaration of function 'openpty'; did you mean 'openat'? [-Wimplicit-function-declaration]
if (openpty(&amaster, aslave, pty_buf, NULL, NULL) < 0) {
^~~~~~~
openat
util/qemu-openpty.c:123:9: warning: nested extern declaration of 'openpty' [-Wnested-externs]
(...)
CC irix-linux-user/linux-user/syscall.o
/qemu-irix/linux-user/syscall.c:6784:22: error: 'F_EXLCK' undeclared here (not in a function); did you mean 'F_RDLCK'?
TRANSTBL_CONVERT(F_EXLCK),
^~~~~~~
/qemu-irix/linux-user/syscall.c:6779:51: note: in definition of macro 'TRANSTBL_CONVERT'
#define TRANSTBL_CONVERT(a) { -1, TARGET_##a, -1, a }
^
/qemu-irix/linux-user/syscall.c:6785:22: error: 'F_SHLCK' undeclared here (not in a function); did you mean 'F_RDLCK'?
TRANSTBL_CONVERT(F_SHLCK),
^~~~~~~
/qemu-irix/linux-user/syscall.c:6779:51: note: in definition of macro 'TRANSTBL_CONVERT'
#define TRANSTBL_CONVERT(a) { -1, TARGET_##a, -1, a }
^
In file included from /qemu-irix/linux-user/syscall.c:121:
/qemu-irix/linux-user/syscall.c: In function 'target_to_host_sigevent':
/qemu-irix/linux-user/syscall.c:7422:27: error: 'struct sigevent' has no member named '_sigev_un'; did you mean 'sigev_value'?
__get_user(host_sevp->_sigev_un._tid, &target_sevp->_sigev_un._tid);
^~~~~~~~~
/qemu-irix/linux-user/qemu.h:501:5: note: in definition of macro '__get_user_e'
((x) = (typeof(*hptr))( \
^
/qemu-irix/linux-user/syscall.c:7422:5: note: in expansion of macro '__get_user'
__get_user(host_sevp->_sigev_un._tid, &target_sevp->_sigev_un._tid);
^~~~~~~~~~
/qemu-irix/linux-user/syscall.c:7422:36: error: '(const bitmask_transtbl *)&<erroneous-expression>' is a pointer; did you mean to use '->'?
__get_user(host_sevp->_sigev_un._tid, &target_sevp->_sigev_un._tid);
^
/qemu-irix/linux-user/qemu.h:501:5: note: in definition of macro '__get_user_e'
((x) = (typeof(*hptr))( \
^
/qemu-irix/linux-user/syscall.c:7422:5: note: in expansion of macro '__get_user'
__get_user(host_sevp->_sigev_un._tid, &target_sevp->_sigev_un._tid);
^~~~~~~~~~
/qemu-irix/linux-user/qemu.h:506:13: warning: left-hand operand of comma expression has no effect [-Wunused-value]
(hptr)), (void)0)
^
/qemu-irix/linux-user/qemu.h:510:31: note: in expansion of macro '__get_user_e'
# define __get_user(x, hptr) __get_user_e(x, hptr, be)
^~~~~~~~~~~~
/qemu-irix/linux-user/syscall.c:7422:5: note: in expansion of macro '__get_user'
__get_user(host_sevp->_sigev_un._tid, &target_sevp->_sigev_un._tid);
^~~~~~~~~~
/qemu-irix/linux-user/syscall.c: In function 'do_syscall':
/qemu-irix/linux-user/syscall.c:13545:25: warning: implicit declaration of function 'sethostid'; did you mean 'gethostid'? [-Wimplicit-function-declaration]
ret = get_errno(sethostid(arg1));
^~~~~~~~~
gethostid
/qemu-irix/linux-user/syscall.c:13545:25: warning: nested extern declaration of 'sethostid' [-Wnested-externs]
make[1]: *** [/qemu-irix/rules.mak:66: linux-user/syscall.o] Error 1
make: *** [Makefile:472: subdir-irix-linux-user] Error 2
The command '/bin/sh -c make && DESTDIR=/tmp/qemu make install' returned a non-zero code: 2
I researched about the differences between Debian's and Alpine's GCC (in fact, libc6 and musl) about similar failures, but I haven't found any information about how to solve this without modifying the code.
So, where can I find more information about this issue and which packages may solve it? Thanks.
Dockerfiles and full log here. Docker container image (Debian Buster) here.

Answer 1

The difference seems to be caused by the underlying libc implementations: glibc of Debian, vs musl-libc of Alpine.
While GNU libc is the defacto standard libc implementation in Linux, musl libc is used by a handful of distributions, such as Alpine Linux and Void Linux. musl is a minimalistic strict-POSIX libc implementation, and is generally not compatible with glibc. Usually, software projects have to be ported to musl libc to be supported on Alpine, especially non trivial applications.
The compilation of syscall.c breaks on several places, the first being:
/qemu-irix/linux-user/syscall.c:6784:22: error: 'F_EXLCK' undeclared here (not in a function); did you mean 'F_RDLCK'?
TRANSTBL_CONVERT(F_EXLCK)
The F_EXLCK is macro is not defined in musl libc's fcntl.h. However, it could be easily patched by defining it manually, for example with make CFLAGS='"-DF_EXLCK=4"'. This is how qemu is patched for musl for non-irix targets (patch link).
However, there are more undefined macros down the road, such as __SIGRTMIN and __SIGRTMAX, the macro TRANSTBL_CONVERT, and probably others. Patching them ad-hoc may not be enough - so it appears to be that the qemu-irix project has to be properly ported for Alpine and musl libc.
If you're willing, you could try following existing qemu musl patches, and attempt to patch it yourself for qemu-irix:
- https://lists.gnu.org/archive/html/qemu-devel/2014-04/msg04773.html
- https://github.com/NixOS/nixpkgs/pull/46449/files
Off topic comment, use make -j to build parallely, which will end much faster.