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authorHenrik Nord <[email protected]>2014-03-21 16:39:02 +0100
committerHenrik Nord <[email protected]>2014-03-21 16:39:05 +0100
commita4030a89eb9a22d250dba2793f274f8731126ea8 (patch)
tree620592b3560f98be67f71f70fd5596cc110ecd70
parentc9da6c2f06efa410462299a20e10206843082ac8 (diff)
parentf43a1dc55d42de3097f75ca65baead9a2ff05c78 (diff)
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Merge branch 'fogfish/embedded-arm-android'
* fogfish/embedded-arm-android: Raspberry PI / Android a minimal cross-compile configuration OTP-11805
-rw-r--r--HOWTO/INSTALL-ANDROID.md52
-rw-r--r--erts/emulator/Makefile.in2
-rw-r--r--erts/emulator/beam/sys.h6
-rw-r--r--erts/emulator/sys/unix/erl_child_setup.c39
-rw-r--r--erts/emulator/sys/unix/erl_unix_sys_ddll.c4
-rw-r--r--erts/emulator/sys/unix/sys.c11
-rw-r--r--erts/etc/common/Makefile.in2
-rw-r--r--erts/lib_src/pthread/ethread.c6
-rw-r--r--lib/erl_interface/src/connect/ei_connect.c4
-rw-r--r--lib/erl_interface/src/connect/ei_resolve.c2
-rw-r--r--lib/kernel/src/os.erl11
-rw-r--r--lib/os_mon/c_src/memsup.c8
-rw-r--r--xcomp/erl-xcomp-arm-android.conf264
13 files changed, 401 insertions, 10 deletions
diff --git a/HOWTO/INSTALL-ANDROID.md b/HOWTO/INSTALL-ANDROID.md
new file mode 100644
index 0000000000..31698d4ce3
--- /dev/null
+++ b/HOWTO/INSTALL-ANDROID.md
@@ -0,0 +1,52 @@
+Cross Compiling Erlang/OTP - ANDROID
+====================================
+
+Introduction
+------------
+
+This document describes how to cross compile Erlang OTP to Android/Rasberry Pi platforms.
+
+### Download and Install Android NDK ###
+
+https://developer.android.com/tools/sdk/ndk/index.html
+
+### Define System Variables ###
+
+export NDK_ROOT=/usr/local/android
+export NDK_PLAT=android-9
+export PATH=$NDK_ROOT/toolchains/arm-linux-androideabi-4.8/prebuilt/darwin-x86_64/bin:$PATH
+
+### Configure OTP ###
+
+./otp_build configure \
+ --xcomp-conf=./xcomp/erl-xcomp-arm-android.conf \
+ --without-ssl
+
+### Compile OTP ###
+
+make noboot [-j4]
+
+### Make Release ###
+
+./otp_build release -a /usr/local/otp_R16B03_arm
+
+### Target Deployment ###
+
+Make a tarball out of /usr/local/otp_R16B03_arm and copy it to target device
+(e.g. Raspberry Pi). Extract it and install
+
+./Install /usr/local/otp_R16B03_arm
+
+Android SDK (adb tool) is used to deploy OTP/Erlang to target device for
+evaluation purpose only.
+
+adb push /usr/local/otp_R16B03_arm /mnt/sdcard/otp_R16B03_arm
+adb shell
+
+### Known Issues ###
+
+ * native inet:gethostbyname/1 return {error, nxdomain} on Raspberry PI. Use dns resolver to by-pass the issue (see http://www.erlang.org/doc/apps/erts/inet_cfg.html)
+
+### References ###
+
+ The port derives some solutions from https://code.google.com/p/erlang4android/
diff --git a/erts/emulator/Makefile.in b/erts/emulator/Makefile.in
index 2a9a0a5c2f..58e77ed1fa 100644
--- a/erts/emulator/Makefile.in
+++ b/erts/emulator/Makefile.in
@@ -378,7 +378,9 @@ LIBS += -l$(ERTS_INTERNAL_LIB)$(TYPEMARKER)
endif # erts_internal_r
+ifneq ($(TARGET),arm-unknown-linux-androideabi)
LIBS += @LIBRT@
+endif
LIBS += @LIBCARBON@
diff --git a/erts/emulator/beam/sys.h b/erts/emulator/beam/sys.h
index e273056a2b..05f07e57b2 100644
--- a/erts/emulator/beam/sys.h
+++ b/erts/emulator/beam/sys.h
@@ -154,10 +154,14 @@ typedef ERTS_SYS_FD_TYPE ErtsSysFdType;
/* In VC++, noreturn is a declspec that has to be before the types,
* but in GNUC it is an att ribute to be placed between return type
* and function name, hence __decl_noreturn <types> __noreturn <function name>
+ *
+ * at some platforms (e.g. Android) __noreturn is defined at sys/cdef.h
*/
#if __GNUC__
# define __decl_noreturn
-# define __noreturn __attribute__((noreturn))
+# ifndef __noreturn
+# define __noreturn __attribute__((noreturn))
+# endif
#else
# if defined(__WIN32__) && defined(_MSC_VER)
# define __noreturn
diff --git a/erts/emulator/sys/unix/erl_child_setup.c b/erts/emulator/sys/unix/erl_child_setup.c
index 7c6e4a2f37..34d7f9e0e5 100644
--- a/erts/emulator/sys/unix/erl_child_setup.c
+++ b/erts/emulator/sys/unix/erl_child_setup.c
@@ -54,6 +54,17 @@ void sys_sigrelease(int sig)
#endif /* !SIG_SIGNAL */
#endif /* !SIG_SIGSET */
+#if defined(__ANDROID__)
+int __system_properties_fd(void);
+#endif /* __ANDROID__ */
+
+#if defined(__ANDROID__)
+#define SHELL "/system/bin/sh"
+#else
+#define SHELL "/bin/sh"
+#endif /* __ANDROID__ */
+
+
int
main(int argc, char *argv[])
{
@@ -89,8 +100,16 @@ main(int argc, char *argv[])
if (sscanf(argv[CS_ARGV_FD_CR_IX], "%d:%d", &from, &to) != 2)
return 1;
+
+#if defined(__ANDROID__)
+ for (i = from; i <= to; i++) {
+ if (i!=__system_properties_fd)
+ (void) close(i);
+ }
+#else
for (i = from; i <= to; i++)
(void) close(i);
+#endif /* __ANDROID__ */
if (!(argv[CS_ARGV_WD_IX][0] == '.' && argv[CS_ARGV_WD_IX][1] == '\0')
&& chdir(argv[CS_ARGV_WD_IX]) < 0)
@@ -116,7 +135,25 @@ main(int argc, char *argv[])
execv(argv[CS_ARGV_NO_OF_ARGS],&(argv[CS_ARGV_NO_OF_ARGS + 1]));
}
} else {
- execl("/bin/sh", "sh", "-c", argv[CS_ARGV_CMD_IX], (char *) NULL);
+ execl(SHELL, "sh", "-c", argv[CS_ARGV_CMD_IX], (char *) NULL);
}
return 1;
}
+
+
+
+#if defined(__ANDROID__)
+int __system_properties_fd(void)
+{
+ int s, fd;
+ char *env;
+
+ env = getenv("ANDROID_PROPERTY_WORKSPACE");
+ if (!env) {
+ return -1;
+ }
+ fd = atoi(env);
+ return fd;
+}
+#endif /* __ANDROID__ */
+
diff --git a/erts/emulator/sys/unix/erl_unix_sys_ddll.c b/erts/emulator/sys/unix/erl_unix_sys_ddll.c
index 8760b58839..2659d623c7 100644
--- a/erts/emulator/sys/unix/erl_unix_sys_ddll.c
+++ b/erts/emulator/sys/unix/erl_unix_sys_ddll.c
@@ -123,6 +123,7 @@ int erts_sys_ddll_open(const char *full_name, void **handle, ErtsSysDdllError* e
int erts_sys_ddll_open_noext(char *dlname, void **handle, ErtsSysDdllError* err)
{
+#if defined(HAVE_DLOPEN)
int ret = ERL_DE_NO_ERROR;
char *str;
dlerror();
@@ -148,6 +149,9 @@ int erts_sys_ddll_open_noext(char *dlname, void **handle, ErtsSysDdllError* err)
ret = ERL_DE_DYNAMIC_ERROR_OFFSET - find_errcode(str, err);
}
return ret;
+#else
+ return ERL_DE_ERROR_NO_DDLL_FUNCTIONALITY;
+#endif
}
/*
diff --git a/erts/emulator/sys/unix/sys.c b/erts/emulator/sys/unix/sys.c
index 865cb50a56..c3d7440409 100644
--- a/erts/emulator/sys/unix/sys.c
+++ b/erts/emulator/sys/unix/sys.c
@@ -149,6 +149,13 @@ extern void erl_crash_dump(char* file, int line, char* fmt, ...);
#define DIR_SEPARATOR_CHAR '/'
+#if defined(__ANDROID__)
+#define SHELL "/system/bin/sh"
+#else
+#define SHELL "/bin/sh"
+#endif /* __ANDROID__ */
+
+
#if defined(DEBUG)
#define ERL_BUILD_TYPE_MARKER ".debug"
#elif defined(PURIFY)
@@ -1596,7 +1603,7 @@ static ErlDrvData spawn_start(ErlDrvPort port_num, char* name, SysDriverOpts* op
}
}
} else {
- execle("/bin/sh", "sh", "-c", cmd_line, (char *) NULL, new_environ);
+ execle(SHELL, "sh", "-c", cmd_line, (char *) NULL, new_environ);
}
child_error:
_exit(1);
@@ -1717,7 +1724,7 @@ static ErlDrvData spawn_start(ErlDrvPort port_num, char* name, SysDriverOpts* op
fcntl(i, F_SETFD, 1);
qnx_spawn_options.flags = _SPAWN_SETSID;
- if ((pid = spawnl(P_NOWAIT, "/bin/sh", "/bin/sh", "-c", cmd_line,
+ if ((pid = spawnl(P_NOWAIT, SHELL, SHELL, "-c", cmd_line,
(char *) 0)) < 0) {
erts_free(ERTS_ALC_T_TMP, (void *) cmd_line);
reset_qnx_spawn();
diff --git a/erts/etc/common/Makefile.in b/erts/etc/common/Makefile.in
index 5c2cd8aded..cfd36af962 100644
--- a/erts/etc/common/Makefile.in
+++ b/erts/etc/common/Makefile.in
@@ -66,7 +66,9 @@ LIBS = @LIBS@
LDFLAGS = @LDFLAGS@
# For clock_gettime in heart
+ifneq ($(TARGET),arm-unknown-linux-androideabi)
RTLIBS = @LIBRT@
+endif
ifeq ($(TARGET),win32)
ifeq ($(TYPE),debug)
diff --git a/erts/lib_src/pthread/ethread.c b/erts/lib_src/pthread/ethread.c
index 7f27b5f29c..79784c5b84 100644
--- a/erts/lib_src/pthread/ethread.c
+++ b/erts/lib_src/pthread/ethread.c
@@ -541,7 +541,11 @@ int ethr_sigmask(int how, const sigset_t *set, sigset_t *oset)
return EINVAL;
}
#endif
- return pthread_sigmask(how, set, oset);
+#if defined(__ANDROID__)
+ return sigprocmask(how, set, oset);
+#else
+ return pthread_sigmask(how, set, oset);
+#endif
}
int ethr_sigwait(const sigset_t *set, int *sig)
diff --git a/lib/erl_interface/src/connect/ei_connect.c b/lib/erl_interface/src/connect/ei_connect.c
index 3175d1bdfd..2e8418d61e 100644
--- a/lib/erl_interface/src/connect/ei_connect.c
+++ b/lib/erl_interface/src/connect/ei_connect.c
@@ -1166,7 +1166,11 @@ static unsigned int gen_challenge(void)
uname(&s.name);
s.cpu = clock();
s.pid = getpid();
+#ifndef __ANDROID__
s.hid = gethostid();
+#else
+ s.hid = 0;
+#endif
s.uid = getuid();
s.gid = getgid();
diff --git a/lib/erl_interface/src/connect/ei_resolve.c b/lib/erl_interface/src/connect/ei_resolve.c
index 74dcba61a7..cffcac801c 100644
--- a/lib/erl_interface/src/connect/ei_resolve.c
+++ b/lib/erl_interface/src/connect/ei_resolve.c
@@ -642,7 +642,7 @@ struct hostent *ei_gethostbyname_r(const char *name,
#ifndef HAVE_GETHOSTBYNAME_R
return my_gethostbyname_r(name,hostp,buffer,buflen,h_errnop);
#else
-#if (defined(__GLIBC__) || (__FreeBSD_version >= 602000) || defined(__DragonFly__))
+#if (defined(__GLIBC__) || (__FreeBSD_version >= 602000) || defined(__DragonFly__) || defined(__ANDROID__))
struct hostent *result;
gethostbyname_r(name, hostp, buffer, buflen, &result, h_errnop);
diff --git a/lib/kernel/src/os.erl b/lib/kernel/src/os.erl
index 9ffa9adeab..3bda391b8e 100644
--- a/lib/kernel/src/os.erl
+++ b/lib/kernel/src/os.erl
@@ -230,7 +230,9 @@ unix_cmd(Cmd) ->
%% and the commands are read from standard input. We set the
%% $1 parameter for easy identification of the resident shell.
%%
--define(SHELL, "/bin/sh -s unix:cmd 2>&1").
+-define(ROOT, "/").
+-define(ROOT_ANDROID, "/system").
+-define(SHELL, "bin/sh -s unix:cmd 2>&1").
-define(PORT_CREATOR_NAME, os_cmd_port_creator).
%%
@@ -280,7 +282,12 @@ start_port_srv(Request) ->
end.
start_port_srv_handle({Ref,Client}) ->
- Reply = try open_port({spawn, ?SHELL},[stream]) of
+ Path = case lists:reverse(erlang:system_info(system_architecture)) of
+ % androideabi
+ "ibaediordna" ++ _ -> filename:join([?ROOT_ANDROID, ?SHELL]);
+ _ -> filename:join([?ROOT, ?SHELL])
+ end,
+ Reply = try open_port({spawn, Path},[stream]) of
Port when is_port(Port) ->
(catch port_connect(Port, Client)),
unlink(Port),
diff --git a/lib/os_mon/c_src/memsup.c b/lib/os_mon/c_src/memsup.c
index b5114d10ed..409db84aa7 100644
--- a/lib/os_mon/c_src/memsup.c
+++ b/lib/os_mon/c_src/memsup.c
@@ -324,7 +324,7 @@ get_mem_procfs(memory_ext *me){
/* arch specific functions */
-#if defined(__linux__) /* ifdef SYSINFO */
+#if defined(__linux__) && !defined(__ANDROID__)/* ifdef SYSINFO */
/* sysinfo does not include cached memory which is a problem. */
static int
get_extended_mem_sysinfo(memory_ext *me) {
@@ -395,8 +395,12 @@ get_extended_mem_sgi(memory_ext *me) {
static void
get_extended_mem(memory_ext *me) {
+/* android */
+#if defined(__ANDROID__)
+ if (get_mem_procfs(me)) return;
+
/* linux */
-#if defined(__linux__)
+#elif defined(__linux__)
if (get_mem_procfs(me)) return;
if (get_extended_mem_sysinfo(me)) return;
diff --git a/xcomp/erl-xcomp-arm-android.conf b/xcomp/erl-xcomp-arm-android.conf
new file mode 100644
index 0000000000..4fd1f270d1
--- /dev/null
+++ b/xcomp/erl-xcomp-arm-android.conf
@@ -0,0 +1,264 @@
+## -*-shell-script-*-
+##
+## %CopyrightBegin%
+##
+## Copyright Ericsson AB 2009-2010. All Rights Reserved.
+##
+## The contents of this file are subject to the Erlang Public License,
+## Version 1.1, (the "License"); you may not use this file except in
+## compliance with the License. You should have received a copy of the
+## Erlang Public License along with this software. If not, it can be
+## retrieved online at http://www.erlang.org/.
+##
+## Software distributed under the License is distributed on an "AS IS"
+## basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
+## the License for the specific language governing rights and limitations
+## under the License.
+##
+## %CopyrightEnd%
+##
+## File: erl-xcomp.conf.template
+## Author:
+##
+## -----------------------------------------------------------------------------
+## When cross compiling Erlang/OTP using `otp_build', copy this file and set
+## the variables needed below. Then pass the path to the copy of this file as
+## an argument to `otp_build' in the configure stage:
+## `otp_build configure --xcomp-conf=<FILE>'
+## -----------------------------------------------------------------------------
+
+## Note that you cannot define arbitrary variables in a cross compilation
+## configuration file. Only the ones listed below will be guaranteed to be
+## visible throughout the whole execution of all `configure' scripts. Other
+## variables needs to be defined as arguments to `configure' or exported in
+## the environment.
+
+## -- Variables for `otp_build' Only -------------------------------------------
+
+## Variables in this section are only used, when configuring Erlang/OTP for
+## cross compilation using `$ERL_TOP/otp_build configure'.
+
+## *NOTE*! These variables currently have *no* effect if you configure using
+## the `configure' script directly.
+
+# * `erl_xcomp_build' - The build system used. This value will be passed as
+# `--build=$erl_xcomp_build' argument to the `configure' script. It does
+# not have to be a full `CPU-VENDOR-OS' triplet, but can be. The full
+# `CPU-VENDOR-OS' triplet will be created by
+# `$ERL_TOP/erts/autoconf/config.sub $erl_xcomp_build'. If set to `guess',
+# the build system will be guessed using
+# `$ERL_TOP/erts/autoconf/config.guess'.
+erl_xcomp_build=guess
+
+# * `erl_xcomp_host' - Cross host/target system to build for. This value will
+# be passed as `--host=$erl_xcomp_host' argument to the `configure' script.
+# It does not have to be a full `CPU-VENDOR-OS' triplet, but can be. The
+# full `CPU-VENDOR-OS' triplet will be created by
+# `$ERL_TOP/erts/autoconf/config.sub $erl_xcomp_host'.
+erl_xcomp_host=arm-linux-androideabi
+
+# * `erl_xcomp_configure_flags' - Extra configure flags to pass to the
+# `configure' script.
+erl_xcomp_configure_flags="--disable-hipe --without-termcap"
+
+
+## -- Cross Compiler and Other Tools -------------------------------------------
+
+##
+##
+NDK_SYSROOT=$NDK_ROOT/platforms/$NDK_PLAT/arch-arm
+
+## If the cross compilation tools are prefixed by `<HOST>-' you probably do
+## not need to set these variables (where `<HOST>' is what has been passed as
+## `--host=<HOST>' argument to `configure').
+
+## All variables in this section can also be used when native compiling.
+
+# * `CC' - C compiler.
+CC="arm-linux-androideabi-gcc --sysroot=$NDK_SYSROOT"
+
+# * `CFLAGS' - C compiler flags.
+CFLAGS="-static -march=armv7-a -msoft-float -mthumb"
+
+# * `STATIC_CFLAGS' - Static C compiler flags.
+#STATIC_CFLAGS=
+
+# * `CFLAG_RUNTIME_LIBRARY_PATH' - This flag should set runtime library
+# search path for the shared libraries. Note that this actually is a
+# linker flag, but it needs to be passed via the compiler.
+#CFLAG_RUNTIME_LIBRARY_PATH=
+
+# * `CPP' - C pre-processor.
+CPP="arm-linux-androideabi-cpp --sysroot=$NDK_SYSROOT"
+
+# * `CPPFLAGS' - C pre-processor flags.
+CPPFLAGS="-static -march=armv7-a -msoft-float -mthumb"
+
+# * `CXX' - C++ compiler.
+CXX="arm-linux-androideabi-c++ --sysroot=$NDK_SYSROOT"
+
+# * `CXXFLAGS' - C++ compiler flags.
+CXXFLAGS="-static -march=armv7-a -msoft-float -mthumb"
+
+# * `LD' - Linker.
+#LD=
+
+# * `LDFLAGS' - Linker flags.
+LDFLAGS="-static -march=armv7-a -msoft-float -mthumb"
+
+# * `LIBS' - Libraries.
+#LIBS=
+
+## -- *D*ynamic *E*rlang *D*river Linking --
+
+## *NOTE*! Either set all or none of the `DED_LD*' variables.
+
+# * `DED_LD' - Linker for Dynamically loaded Erlang Drivers.
+#DED_LD=
+
+# * `DED_LDFLAGS' - Linker flags to use with `DED_LD'.
+#DED_LDFLAGS=
+
+# * `DED_LD_FLAG_RUNTIME_LIBRARY_PATH' - This flag should set runtime library
+# search path for shared libraries when linking with `DED_LD'.
+#DED_LD_FLAG_RUNTIME_LIBRARY_PATH=
+
+## -- Large File Support --
+
+## *NOTE*! Either set all or none of the `LFS_*' variables.
+
+# * `LFS_CFLAGS' - Large file support C compiler flags.
+#LFS_CFLAGS=
+
+# * `LFS_LDFLAGS' - Large file support linker flags.
+#LFS_LDFLAGS=
+
+# * `LFS_LIBS' - Large file support libraries.
+#LFS_LIBS=
+
+## -- Other Tools --
+
+# * `RANLIB' - `ranlib' archive index tool.
+#RANLIB=
+
+# * `AR' - `ar' archiving tool.
+#AR=
+
+# * `GETCONF' - `getconf' system configuration inspection tool. `getconf' is
+# currently used for finding out large file support flags to use, and
+# on Linux systems for finding out if we have an NPTL thread library or
+# not.
+#GETCONF=
+
+## -- Cross System Root Locations ----------------------------------------------
+
+# * `erl_xcomp_sysroot' - The absolute path to the system root of the cross
+# compilation environment. Currently, the `crypto', `odbc', `ssh' and
+# `ssl' applications need the system root. These applications will be
+# skipped if the system root has not been set. The system root might be
+# needed for other things too. If this is the case and the system root
+# has not been set, `configure' will fail and request you to set it.
+erl_xcomp_sysroot="$NDK_SYSROOT"
+
+
+# * `erl_xcomp_isysroot' - The absolute path to the system root for includes
+# of the cross compilation environment. If not set, this value defaults
+# to `$erl_xcomp_sysroot', i.e., only set this value if the include system
+# root path is not the same as the system root path.
+#erl_xcomp_isysroot=
+
+## -- Optional Feature, and Bug Tests ------------------------------------------
+
+## These tests cannot (always) be done automatically when cross compiling. You
+## usually do not need to set these variables. Only set these if you really
+## know what you are doing.
+
+## Note that some of these values will override results of tests performed
+## by `configure', and some will not be used until `configure' is sure that
+## it cannot figure the result out.
+
+## The `configure' script will issue a warning when a default value is used.
+## When a variable has been set, no warning will be issued.
+
+# * `erl_xcomp_after_morecore_hook' - `yes|no'. Defaults to `no'. If `yes',
+# the target system must have a working `__after_morecore_hook' that can be
+# used for tracking used `malloc()' implementations core memory usage.
+# This is currently only used by unsupported features.
+#erl_xcomp_after_morecore_hook=
+
+# * `erl_xcomp_bigendian' - `yes|no'. No default. If `yes', the target system
+# must be big endian. If `no', little endian. This can often be
+# automatically detected, but not always. If not automatically detected,
+# `configure' will fail unless this variable is set. Since no default
+# value is used, `configure' will try to figure this out automatically.
+#erl_xcomp_bigendian=
+
+# * `erl_xcomp_clock_gettime_cpu_time' - `yes|no'. Defaults to `no'. If `yes',
+# the target system must have a working `clock_gettime()' implementation
+# that can be used for retrieving process CPU time.
+#erl_xcomp_clock_gettime_cpu_time=
+
+# * `erl_xcomp_getaddrinfo' - `yes|no'. Defaults to `no'. If `yes', the target
+# system must have a working `getaddrinfo()' implementation that can
+# handle both IPv4 and IPv6.
+#erl_xcomp_getaddrinfo=
+
+# * `erl_xcomp_gethrvtime_procfs_ioctl' - `yes|no'. Defaults to `no'. If `yes',
+# the target system must have a working `gethrvtime()' implementation and
+# is used with procfs `ioctl()'.
+#erl_xcomp_gethrvtime_procfs_ioctl=
+
+# * `erl_xcomp_dlsym_brk_wrappers' - `yes|no'. Defaults to `no'. If `yes', the
+# target system must have a working `dlsym(RTLD_NEXT, <S>)' implementation
+# that can be used on `brk' and `sbrk' symbols used by the `malloc()'
+# implementation in use, and by this track the `malloc()' implementations
+# core memory usage. This is currently only used by unsupported features.
+#erl_xcomp_dlsym_brk_wrappers=
+
+# * `erl_xcomp_kqueue' - `yes|no'. Defaults to `no'. If `yes', the target
+# system must have a working `kqueue()' implementation that returns a file
+# descriptor which can be used by `poll()' and/or `select()'. If `no' and
+# the target system has not got `epoll()' or `/dev/poll', the kernel-poll
+# feature will be disabled.
+#erl_xcomp_kqueue=
+
+# * `erl_xcomp_linux_clock_gettime_correction' - `yes|no'. Defaults to `yes' on
+# Linux; otherwise, `no'. If `yes', `clock_gettime(CLOCK_MONOTONIC, _)' on
+# the target system must work. This variable is recommended to be set to
+# `no' on Linux systems with kernel versions less than 2.6.
+#erl_xcomp_linux_clock_gettime_correction=
+
+# * `erl_xcomp_linux_nptl' - `yes|no'. Defaults to `yes' on Linux; otherwise,
+# `no'. If `yes', the target system must have NPTL (Native POSIX Thread
+# Library). Older Linux systems have LinuxThreads instead of NPTL (Linux
+# kernel versions typically less than 2.6).
+#erl_xcomp_linux_nptl=
+
+# * `erl_xcomp_linux_usable_sigaltstack' - `yes|no'. Defaults to `yes' on Linux;
+# otherwise, `no'. If `yes', `sigaltstack()' must be usable on the target
+# system. `sigaltstack()' on Linux kernel versions less than 2.4 are
+# broken.
+#erl_xcomp_linux_usable_sigaltstack=
+
+# * `erl_xcomp_linux_usable_sigusrx' - `yes|no'. Defaults to `yes'. If `yes',
+# the `SIGUSR1' and `SIGUSR2' signals must be usable by the ERTS. Old
+# LinuxThreads thread libraries (Linux kernel versions typically less than
+# 2.2) used these signals and made them unusable by the ERTS.
+#erl_xcomp_linux_usable_sigusrx=
+
+# * `erl_xcomp_poll' - `yes|no'. Defaults to `no' on Darwin/MacOSX; otherwise,
+# `yes'. If `yes', the target system must have a working `poll()'
+# implementation that also can handle devices. If `no', `select()' will be
+# used instead of `poll()'.
+#erl_xcomp_poll=
+
+# * `erl_xcomp_putenv_copy' - `yes|no'. Defaults to `no'. If `yes', the target
+# system must have a `putenv()' implementation that stores a copy of the
+# key/value pair.
+#erl_xcomp_putenv_copy=
+
+# * `erl_xcomp_reliable_fpe' - `yes|no'. Defaults to `no'. If `yes', the target
+# system must have reliable floating point exceptions.
+#erl_xcomp_reliable_fpe=
+
+## -----------------------------------------------------------------------------