There are cases where one might want to run programs with the GNU ABI on
an Android device, such as running Gentoo Prefix inside an Android app
like Termux that provides a POSIX-like environment. This mostly works
out-of-the-box; however, there are certain edge cases when running on a
system with an Android kernel/userspace. Most notably, only certain
syscalls are allowed under Android's seccomp policy, with all others
blocked by default, even if the kernel would otherwise support it.
Glibc's modus operandi when running under Linux is to try to perform the
newer syscall first, and if it is not supported by the kernel, fall back
to the older implementation. Under this seccomp policy this doesn't
work, and programs are simply terminated without being given a chance to
fall back. To make Glibc and other software avoid performing these
syscalls when running Android, we must let them know at configure time
that the target system does not allow performing these syscalls. Setting
the vendor to "android" lets us tell the software that even though the
GNU ABI is in effect, certain restrictions are present due to running on
Android.
Android only supports aarch64, arm, i*86 and x86_64 arches, therefore
the vendor is only set there.
* config.guess (*-android-linux-*): Recognize.
Signed-off-by: sin-ack <sin-...@protonmail.com>
---
config.guess | 36 ++++++++++++++++++++++++++++--------
1 file changed, 28 insertions(+), 8 deletions(-)
diff --git a/config.guess b/config.guess
index 48a6846..f3407f6 100755
--- a/config.guess
+++ b/config.guess
@@ -4,7 +4,7 @@
# shellcheck disable=SC2006,SC2268 # see below for rationale
-timestamp='2024-07-27'
+timestamp='2025-04-05'
# This file is free software; you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by
@@ -191,6 +191,20 @@ Linux|GNU|GNU/*)
if [ "$LIBC" = unknown ]; then
LIBC=gnu
fi
+
+ # Check if we're actually running on an Android system. It's possible that
the user
+ # wants to use the GNU ABI, but is actually running on Android. There is a
certain
+ # amount of caution that must be taken due to the seccomp policy present
on Android
+ # systems, which prevents certain syscalls from being even attempted, thus
we must
+ # differentiate between a regular Linux system and Android.
+ VENDOR=unknown
+ if test -c "/dev/ashmem"; then
+ # /dev/ashmem is an Android-specific shared memory device.
+ VENDOR=android
+ elif test -f "/system/bin/linker"; then
+ # The Android dynamic linker must always be present on Android systems.
+ VENDOR=android
+ fi
;;
esac
@@ -1004,11 +1018,11 @@ EOF
eabi | eabihf) CPU=armv8l; LIBCABI=$LIBC$ABI ;;
esac
fi
- GUESS=$CPU-unknown-linux-$LIBCABI
+ GUESS=$CPU-$VENDOR-linux-$LIBCABI
;;
aarch64_be:Linux:*:*)
UNAME_MACHINE=aarch64_be
- GUESS=$UNAME_MACHINE-unknown-linux-$LIBC
+ GUESS=$UNAME_MACHINE-$VENDOR-linux-$LIBC
;;
alpha:Linux:*:*)
case `sed -n '/^cpu model/s/^.*: \(.*\)/\1/p' /proc/cpuinfo
2>/dev/null` in
@@ -1032,14 +1046,14 @@ EOF
if echo __ARM_EABI__ | $CC_FOR_BUILD -E - 2>/dev/null \
| grep -q __ARM_EABI__
then
- GUESS=$UNAME_MACHINE-unknown-linux-$LIBC
+ GUESS=$UNAME_MACHINE-$VENDOR-linux-$LIBC
else
if echo __ARM_PCS_VFP | $CC_FOR_BUILD -E - 2>/dev/null \
| grep -q __ARM_PCS_VFP
then
- GUESS=$UNAME_MACHINE-unknown-linux-${LIBC}eabi
+ GUESS=$UNAME_MACHINE-$VENDOR-linux-${LIBC}eabi
else
- GUESS=$UNAME_MACHINE-unknown-linux-${LIBC}eabihf
+ GUESS=$UNAME_MACHINE-$VENDOR-linux-${LIBC}eabihf
fi
fi
;;
@@ -1062,7 +1076,10 @@ EOF
GUESS=$UNAME_MACHINE-unknown-linux-$LIBC
;;
i*86:Linux:*:*)
- GUESS=$UNAME_MACHINE-pc-linux-$LIBC
+ if [ "$VENDOR" = unknown ]; then
+ VENDOR=pc
+ fi
+ GUESS=$UNAME_MACHINE-$VENDOR-linux-$LIBC
;;
ia64:Linux:*:*)
GUESS=$UNAME_MACHINE-unknown-linux-$LIBC
@@ -1214,7 +1231,10 @@ EOF
x32) LIBCABI=${LIBC}x32 ;;
esac
fi
- GUESS=$CPU-pc-linux-$LIBCABI
+ if [ "$VENDOR" = unknown ]; then
+ VENDOR=pc
+ fi
+ GUESS=$CPU-$VENDOR-linux-$LIBCABI
;;
xtensa*:Linux:*:*)
GUESS=$UNAME_MACHINE-unknown-linux-$LIBC
--
2.45.3
