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-rw-r--r--Documentation/filesystems/dax.txt3
-rw-r--r--fs/Kconfig1
2 files changed, 4 insertions, 0 deletions
diff --git a/Documentation/filesystems/dax.txt b/Documentation/filesystems/dax.txt
index be376d91d058..baf41118660d 100644
--- a/Documentation/filesystems/dax.txt
+++ b/Documentation/filesystems/dax.txt
@@ -82,6 +82,9 @@ Shortcomings
Even if the kernel or its modules are stored on a filesystem that supports
DAX on a block device that supports DAX, they will still be copied into RAM.
+The DAX code does not work correctly on architectures which have virtually
+mapped caches such as ARM, MIPS and SPARC.
+
Calling get_user_pages() on a range of user memory that has been mmaped
from a DAX file will fail as there are no 'struct page' to describe
those pages. This problem is being worked on. That means that O_DIRECT
diff --git a/fs/Kconfig b/fs/Kconfig
index 5331497d5b25..ec35851e5b71 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -36,6 +36,7 @@ source "fs/nilfs2/Kconfig"
config FS_DAX
bool "Direct Access (DAX) support"
depends on MMU
+ depends on !(ARM || MIPS || SPARC)
help
Direct Access (DAX) can be used on memory-backed block devices.
If the block device supports DAX and the filesystem supports DAX,