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authorRalf Baechle <ralf@linux-mips.org>2010-08-17 16:01:59 +0100
committerRalf Baechle <ralf@linux-mips.org>2010-10-04 18:33:55 +0100
commit5707bf6bcecd85d01ea22e8b28cf66170068475f (patch)
tree7e816313c963b856caceb6611928cb1fa98929ce
parent1ec0e739766b29c9d93d8a4cff68b1cb2e962cde (diff)
MIPS: Document why RELOC_HIDE is there.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
-rw-r--r--arch/mips/include/asm/page.h14
1 files changed, 14 insertions, 0 deletions
diff --git a/arch/mips/include/asm/page.h b/arch/mips/include/asm/page.h
index a16beafcea9..e59cd1ac09c 100644
--- a/arch/mips/include/asm/page.h
+++ b/arch/mips/include/asm/page.h
@@ -150,6 +150,20 @@ typedef struct { unsigned long pgprot; } pgprot_t;
((unsigned long)(x) - PAGE_OFFSET + PHYS_OFFSET)
#endif
#define __va(x) ((void *)((unsigned long)(x) + PAGE_OFFSET - PHYS_OFFSET))
+
+/*
+ * RELOC_HIDE was originally added by 6007b903dfe5f1d13e0c711ac2894bdd4a61b1ad
+ * (lmo) rsp. 8431fd094d625b94d364fe393076ccef88e6ce18 (kernel.org). The
+ * discussion can be found in lkml posting
+ * <a2ebde260608230500o3407b108hc03debb9da6e62c@mail.gmail.com> which is
+ * archived at http://lists.linuxcoding.com/kernel/2006-q3/msg17360.html
+ *
+ * It is unclear if the misscompilations mentioned in
+ * http://lkml.org/lkml/2010/8/8/138 also affect MIPS so we keep this one
+ * until GCC 3.x has been retired before we can apply
+ * https://patchwork.linux-mips.org/patch/1541/
+ */
+
#define __pa_symbol(x) __pa(RELOC_HIDE((unsigned long)(x), 0))
#define pfn_to_kaddr(pfn) __va((pfn) << PAGE_SHIFT)