Clozure CL on musl systems

Back when I wrote this admittedly shoddy monkey patch, it was probably the simplest way to get a Lisp system running under musl. Nowadays ECL should be able to do the job. I would have upstreamed this, but see below. This page mostly exists for historical reasons but maybe somebody will find it useful.

The compatibility issues are:

CCL uses the glibc-specific name of an anonymous struct; we define a compatible one.
mcheck.h is a glibc extension and should be guarded behind __GLIBC__, not ANDROID. It's optional, so we disable it. I don't know anything about Android so I kept the no Android rule.
gnu_get_libc_version obviously only exists on glibc; it gets dummied out.
fpucontrol.h is glibc-specific but appears to be unused anyway.
I don't recall anymore why -no-pie is necessary. I think it's because GCC is now commonly configured to emit PIE code and some of the assembly sections aren't position-independent? Doesn't explain why this isn't an issue under glibc though… That's what you get for documenting things four years later.
CCL relies on implementation details for dynamic loading of SOs. In particular, the DT_STRTAB entry is an offset in musl and the load address in glibc. There should be a way to do this portably through .dynsym from the ELF file, but I think it might be better to just replace the entire code with a few lines of portable C. Otherwise you would have to introduce a musl feature, which is a pain because musl doesn't provide detection macros (for good reason). This part is the reason I never upstreamed anything.

--- ccl/lisp-kernel/lisp-debug.c	2017-11-29 00:25:49.000000000 +0100
+++ ccl_patched/lisp-kernel/lisp-debug.c	2018-04-07 00:23:43.000000000 +0200
@@ -22,6 +22,7 @@
 #include <ctype.h>
 #include <stdio.h>
 #include <stddef.h>
+#include <stdint.h>
 #include <string.h>
 #include <stdarg.h>
 #include <errno.h>
@@ -1134,6 +1135,11 @@
   return debug_continue;
 }

+#if X8664 && defined(LINUX)
+struct x8664_xmmreg {
+  uint32_t element[4];
+};
+#endif

 debug_command_return
 debug_show_fpu(ExceptionInformation *xp, siginfo_t *info, int arg)
@@ -1151,7 +1158,7 @@
 #endif
 #ifdef X8664
 #ifdef LINUX
-  struct _libc_xmmreg * xmmp = NULL;
+  struct x8664_xmmreg * xmmp = NULL;
 #endif
 #ifdef DARWIN
   struct xmm {
@@ -1175,7 +1182,7 @@

 #ifdef LINUX
   if (xp->uc_mcontext.fpregs)
-    xmmp = &(xp->uc_mcontext.fpregs->_xmm[0]);
+    xmmp = (struct x8664_xmmreg*)&(xp->uc_mcontext.fpregs->_xmm[0]);
   else
     /* no fp state, apparently */
     return debug_continue;
--- ccl/lisp-kernel/pmcl-kernel.c	2017-11-29 00:25:49.000000000 +0100
+++ ccl_patched/lisp-kernel/pmcl-kernel.c	2018-04-07 19:14:15.000000000 +0200
@@ -35,7 +35,7 @@
 #endif

 #ifdef LINUX
-#ifndef ANDROID
+#if !defined(ANDROID) && defined(__GLIBC__)
 #include <mcheck.h>
 #endif
 #include <dirent.h>
@@ -1711,6 +1711,16 @@
 #include <asm/prctl.h>
 #include <sys/prctl.h>

+#ifndef __GLIBC__
+static char *
+gnu_get_libc_version(void)
+{
+	static char ver[] = "(not glibc)";
+
+	return ver;
+}
+#endif
+
 void
 ensure_gs_available(char *progname)
 {
--- ccl/lisp-kernel/x86-exceptions.c	2017-11-29 00:25:49.000000000 +0100
+++ ccl_patched/lisp-kernel/x86-exceptions.c	2018-04-02 21:22:36.000000000 +0200
@@ -29,7 +29,6 @@
 #ifdef LINUX
 #include <strings.h>
 #include <sys/mman.h>
-#include <fpu_control.h>
 #include <linux/prctl.h>
 #endif
 #ifdef DARWIN
--- ccl/lisp-kernel/linuxx8664/Makefile	2017-11-29 00:25:49.000000000 +0100
+++ ccl_patched/lisp-kernel/linuxx8664/Makefile	2018-04-03 05:31:45.000000000 +0200
@@ -22,7 +22,7 @@
 ASFLAGS = --64
 M4FLAGS = -DLINUX -DX86 -DX8664 -DHAVE_TLS
 CDEFINES = -DLINUX -D_REENTRANT -DX86 -DX8664 -D_GNU_SOURCE -DHAVE_TLS  -DVC_REVISION=$(VC_REVISION) #-DDISABLE_EGC -DUSE_FUTEX
 CDEBUG = -g
-COPT = -O2
+COPT = -O2 -fno-pie
 # Once in a while, -Wformat says something useful.  The odds are against that,
 # however.
@@ -75,4 +75,4 @@

 ../../lx86cl64: $(KSPOBJ) $(KERNELOBJ) $(DEBUGOBJ) Makefile  $(LINK_MAP)
-	$(CC)  -m64 $(CDEBUG)  -Wl,--export-dynamic $(HASH_STYLE) -o $@ $(USE_LINK_MAP) $(KSPOBJ) $(KERNELOBJ) $(DEBUGOBJ) -Wl,--no-as-needed $(OSLIBS)
+	$(CC) -no-pie -m64 $(CDEBUG)  -Wl,--export-dynamic $(HASH_STYLE) -o $@ $(USE_LINK_MAP) $(KSPOBJ) $(KERNELOBJ) $(DEBUGOBJ) -Wl,--no-as-needed $(OSLIBS)

--- ccl/level-0/l0-cfm-support.lisp	2017-11-29 00:25:49.000000000 +0100
+++ ccl_patched/level-0/l0-cfm-support.lisp	2018-04-07 19:53:25.000000000 +0200
@@ -233,10 +233,8 @@
					     (if (and (> udisp (pref map :link_map.l_addr))
						      (< udisp (%ptr-to-int dynamic-entries)))
					       (%int-to-ptr udisp)
					       (%int-to-ptr 
-                                               (if (< disp 0) 
-                                                 (+ disp (pref map :link_map.l_addr))
-                                                 disp))))))))
+                                               (+ disp (pref map :link_map.l_addr)))))))))
		 (%setf-macptr dynamic-entries
			       (%inc-ptr dynamic-entries
					 #+32-bit-target