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void __iomem * __arm_ioremap_pfn_caller(unsigned long pfn, /* * Don't allow RAM to be mapped - this causes problems with ARMv6+ */ if (WARN_ON(pfn_valid(pfn))) return NULL;
commit 576d2f2525612ecb5af029a76f21f22a3b82563d Author: Nicolas Pitre <nicolas.pitre@linaro.org> Date: Fri Sep 16 01:14:23 2011 -0400 ARM: add generic ioremap optimization by reusing static mappings Now that we have all the static mappings from iotable_init() located in the vmalloc area, it is trivial to optimize ioremap by reusing those static mappings when the requested physical area fits in one of them, and so in a generic way for all platforms. Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org> Tested-by: Stephen Warren <swarren@nvidia.com> Tested-by: Kevin Hilman <khilman@ti.com> Tested-by: Jamie Iles <jamie@jamieiles.com>この手前で、vmlistの領域に引っかかっていれば、そのアドレスを返している(ioremapした空間だと思われ)。
commit 309caa9cc6ff39d261264ec4ff10e29489afc8f8 Author: Russell King <rmk+kernel@arm.linux.org.uk> Date: Mon Jun 21 21:03:18 2010 +0100 ARM: Prohibit ioremap() on kernel managed RAM ARMv6 and above have a restriction whereby aliasing virtual:physical mappings must not have differing memory type and sharability attributes. Strictly, this covers the memory type (strongly ordered, device, memory), cache attributes (uncached, write combine, write through, write back read alloc, write back write alloc) and the shared bit. However, using ioremap() and its variants on system RAM results in mappings which differ in these attributes from the main system RAM mapping. Other architectures which similar restrictions approch this problem in the same way - they do not permit ioremap on main system RAM. Make ARM behave in the same way, with a WARN_ON() such that users can be traced and an alternative approach found. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>FILE: arch/arm/mm/ioremap.c