mirror_zfs/config/kernel-stdarg.m4
Alexander a3588c68f7
Linux 5.15 compat: standalone <linux/stdarg.h>
Kernel commits

39f75da7bcc8 ("isystem: trim/fixup stdarg.h and other headers")
c0891ac15f04 ("isystem: ship and use stdarg.h")
564f963eabd1 ("isystem: delete global -isystem compile option")

(for now can be found in linux-next.git tree, will land into the
 Linus' tree during the ongoing 5.15 cycle with one of akpm merges)

removed the -isystem flag and disallowed the inclusion of any
compiler header files. They also introduced a minimal
<linux/stdarg.h> as a replacement for <stdarg.h>.
include/os/linux/spl/sys/cmn_err.h in the ZFS source tree includes
<stdarg.h> unconditionally. Introduce a test for <linux/stdarg.h>
and include it instead of the compiler's one to prevent module
build breakage.

Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Alexander Lobakin <alobakin@pm.me>
Closes #12531
2021-09-08 12:59:43 -07:00

33 lines
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dnl #
dnl # Linux 5.15 gets rid of -isystem and external <stdarg.h> inclusion
dnl # and ships its own <linux/stdarg.h>. Check if this header file does
dnl # exist and provide all necessary definitions for variable argument
dnl # functions. Adjust the inclusion of <stdarg.h> according to the
dnl # results.
dnl #
AC_DEFUN([ZFS_AC_KERNEL_SRC_STANDALONE_LINUX_STDARG], [
ZFS_LINUX_TEST_SRC([has_standalone_linux_stdarg], [
#include <linux/stdarg.h>
#if !defined(va_start) || !defined(va_end) || \
!defined(va_arg) || !defined(va_copy)
#error "<linux/stdarg.h> is invalid"
#endif
],[])
])
AC_DEFUN([ZFS_AC_KERNEL_STANDALONE_LINUX_STDARG], [
dnl #
dnl # Linux 5.15 ships its own stdarg.h and doesn't allow to
dnl # include compiler headers.
dnl #
AC_MSG_CHECKING([whether standalone <linux/stdarg.h> exists])
ZFS_LINUX_TEST_RESULT([has_standalone_linux_stdarg], [
AC_MSG_RESULT([yes])
AC_DEFINE(HAVE_STANDALONE_LINUX_STDARG, 1,
[standalone <linux/stdarg.h> exists])
],[
AC_MSG_RESULT([no])
])
])