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e191b54ecf
Certain versions of gcc generate an 'unrecognized command
line option' error message when -Wunused-but-set-variable
is used unconditionally. This in turn can cause several
of the autoconf tests to misdetect an interface.
Now, the use of -Wunused-but-set-variable in the autoconf
tests was introduced by commit b9c59ec8 to address a gcc
4.6 compatibility problem. So we really only need to pass
this option for version of gcc which are known to support it.
Therefore, the tests have been updated to use the result of
the existing ZFS_AC_CONFIG_ALWAYS_NO_UNUSED_BUT_SET_VARIABLE
which determines if gcc supports this option.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1004
40 lines
1.5 KiB
Plaintext
40 lines
1.5 KiB
Plaintext
dnl #
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dnl # 2.6.30 API change
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dnl #
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dnl # The bdev_physical_block_size() interface was added to provide a way
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dnl # to determine the smallest write which can be performed without a
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dnl # read-modify-write operation. From the kernel documentation:
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dnl #
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dnl # What: /sys/block/<disk>/queue/physical_block_size
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dnl # Date: May 2009
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dnl # Contact: Martin K. Petersen <martin.petersen@oracle.com>
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dnl # Description:
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dnl # This is the smallest unit the storage device can write
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dnl # without resorting to read-modify-write operation. It is
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dnl # usually the same as the logical block size but may be
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dnl # bigger. One example is SATA drives with 4KB sectors
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dnl # that expose a 512-byte logical block size to the
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dnl # operating system.
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dnl #
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dnl # Unfortunately, this interface isn't entirely reliable because
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dnl # drives are sometimes known to misreport this value.
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dnl #
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AC_DEFUN([ZFS_AC_KERNEL_BDEV_PHYSICAL_BLOCK_SIZE], [
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AC_MSG_CHECKING([whether bdev_physical_block_size() is available])
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tmp_flags="$EXTRA_KCFLAGS"
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EXTRA_KCFLAGS="${NO_UNUSED_BUT_SET_VARIABLE}"
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ZFS_LINUX_TRY_COMPILE([
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#include <linux/blkdev.h>
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],[
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struct block_device *bdev = NULL;
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bdev_physical_block_size(bdev);
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],[
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AC_MSG_RESULT(yes)
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AC_DEFINE(HAVE_BDEV_PHYSICAL_BLOCK_SIZE, 1,
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[bdev_physical_block_size() is available])
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],[
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AC_MSG_RESULT(no)
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])
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EXTRA_KCFLAGS="$tmp_flags"
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])
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