This patch relaxes the restriction set by commit 309caa9cc, which prohibit ioremap() on all kernel managed pages.
Other architectures, such as x86 and (some specific platforms of) powerpc, allow such mapping. ioremap() pages is an efficient way to avoid arm's mysterious cache control. This feature will be used for arm kexec support to ensure copied data goes into RAM even without cache flushing, because we found that flush_cache_xxx can't reliably flush code to memory. Signed-off-by: Wang Nan <[email protected]> Cc: <[email protected]> # 3.4+ Cc: Eric Biederman <[email protected]> Cc: Russell King <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Geng Hui <[email protected]> --- arch/arm/mm/ioremap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/arm/mm/ioremap.c b/arch/arm/mm/ioremap.c index f123d6e..98b1c10 100644 --- a/arch/arm/mm/ioremap.c +++ b/arch/arm/mm/ioremap.c @@ -298,7 +298,7 @@ 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))) + if (WARN_ON(pfn_valid(pfn) && !PageReserved(pfn_to_page(pfn)))) return NULL; area = get_vm_area_caller(size, VM_IOREMAP, caller); -- 1.8.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
