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Diffstat (limited to 'Documentation/driver-api/device-io.rst')
| -rw-r--r-- | Documentation/driver-api/device-io.rst | 9 |
1 files changed, 5 insertions, 4 deletions
diff --git a/Documentation/driver-api/device-io.rst b/Documentation/driver-api/device-io.rst index 2c7abd234f4e..d55384b106bd 100644 --- a/Documentation/driver-api/device-io.rst +++ b/Documentation/driver-api/device-io.rst @@ -408,11 +408,12 @@ functions for details on the CPU side of things. ioremap_uc() ------------ -ioremap_uc() behaves like ioremap() except that on the x86 architecture without -'PAT' mode, it marks memory as uncached even when the MTRR has designated -it as cacheable, see Documentation/arch/x86/pat.rst. +ioremap_uc() is only meaningful on old x86-32 systems with the PAT extension, +and on ia64 with its slightly unconventional ioremap() behavior, everywhere +elss ioremap_uc() defaults to return NULL. -Portable drivers should avoid the use of ioremap_uc(). + +Portable drivers should avoid the use of ioremap_uc(), use ioremap() instead. ioremap_cache() --------------- |