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authorRussell King <rmk@dyn-67.arm.linux.org.uk>2007-04-21 10:16:48 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2007-04-21 20:35:52 +0100
commit4a56c1e41f19393577bdd5c774c289c199b7269d (patch)
treea2c36198e3b4d78ccc8e373c3748112bc0645b0e /arch/arm/mm/ioremap.c
parentd5c98176ef34b8b78645646593c17e10f62f53ff (diff)
[ARM] mm 3: separate out supersection mappings, avoid for <4GB
Catalin Marinas at ARM Ltd says: > The CPU architects in ARM intended supersections only as a way to map > addresses >= 4GB. Supersections are not mandated by the architecture > and there is no easy way to detect their hardware support at run-time > (other than checking for a specific core). From the analysis done in > ARM, there wasn't a clear performance gain by using supersections > rather than sections (no significant improvement in the TLB misses). Therefore, we should avoid using supersections unless there's a real need (iow, we're mapping addresses >= 4GB). This means that we can simplify create_mapping() a bit since we will only use supersection mappings for addresses >= 4GB, which means that the physical, virtual and length must be multiples of the supersection mapping size. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/mm/ioremap.c')
-rw-r--r--arch/arm/mm/ioremap.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/arm/mm/ioremap.c b/arch/arm/mm/ioremap.c
index 0ac615c0f79..800855b2dc8 100644
--- a/arch/arm/mm/ioremap.c
+++ b/arch/arm/mm/ioremap.c
@@ -302,7 +302,7 @@ __ioremap_pfn(unsigned long pfn, unsigned long offset, size_t size,
#ifndef CONFIG_SMP
if (DOMAIN_IO == 0 &&
(((cpu_architecture() >= CPU_ARCH_ARMv6) && (get_cr() & CR_XP)) ||
- cpu_is_xsc3()) &&
+ cpu_is_xsc3()) && pfn >= 0x100000 &&
!((__pfn_to_phys(pfn) | size | addr) & ~SUPERSECTION_MASK)) {
area->flags |= VM_ARM_SECTION_MAPPING;
err = remap_area_supersections(addr, pfn, size, flags);