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Diffstat (limited to 'config/kernel-bdev-physical-size.m4')
| -rw-r--r-- | config/kernel-bdev-physical-size.m4 | 39 |
1 files changed, 39 insertions, 0 deletions
diff --git a/config/kernel-bdev-physical-size.m4 b/config/kernel-bdev-physical-size.m4 new file mode 100644 index 000000000..0a1fe8e26 --- /dev/null +++ b/config/kernel-bdev-physical-size.m4 @@ -0,0 +1,39 @@ +dnl # +dnl # 2.6.30 API change +dnl # +dnl # The bdev_physical_block_size() interface was added to provide a way +dnl # to determine the smallest write which can be performed without a +dnl # read-modify-write operation. From the kernel documentation: +dnl # +dnl # What: /sys/block/<disk>/queue/physical_block_size +dnl # Date: May 2009 +dnl # Contact: Martin K. Petersen <[email protected]> +dnl # Description: +dnl # This is the smallest unit the storage device can write +dnl # without resorting to read-modify-write operation. It is +dnl # usually the same as the logical block size but may be +dnl # bigger. One example is SATA drives with 4KB sectors +dnl # that expose a 512-byte logical block size to the +dnl # operating system. +dnl # +dnl # Unfortunately, this interface isn't entirely reliable because +dnl # drives are sometimes known to misreport this value. +dnl # +AC_DEFUN([ZFS_AC_KERNEL_BDEV_PHYSICAL_BLOCK_SIZE], [ + AC_MSG_CHECKING([whether bdev_physical_block_size() is available]) + tmp_flags="$EXTRA_KCFLAGS" + EXTRA_KCFLAGS="-Wno-unused-but-set-variable" + ZFS_LINUX_TRY_COMPILE([ + #include <linux/blkdev.h> + ],[ + struct block_device *bdev = NULL; + bdev_physical_block_size(bdev); + ],[ + AC_MSG_RESULT(yes) + AC_DEFINE(HAVE_BDEV_PHYSICAL_BLOCK_SIZE, 1, + [bdev_physical_block_size() is available]) + ],[ + AC_MSG_RESULT(no) + ]) + EXTRA_KCFLAGS="$tmp_flags" +]) |