[POWERPC] Tweak VDSO linker script to avoid upsetting old binutils

[linux-2.6-omap-h63xx.git] / include / asm-powerpc / ppc_asm.h

diff --git a/include/asm-powerpc/ppc_asm.h b/include/asm-powerpc/ppc_asm.h
index 2dbd4e7884faee59e96e53b391e1495bee1307e2..ef96bfd4ef4cbda90bb6827a75e6911ff7386ad0 100644 (file)
--- a/include/asm-powerpc/ppc_asm.h
+++ b/include/asm-powerpc/ppc_asm.h
@@ -356,6 +356,12 @@ END_FTR_SECTION_IFCLR(CPU_FTR_601)
 #define toreal(rd)
 #define fromreal(rd)
 
+/*
+ * We use addis to ensure compatibility with the "classic" ppc versions of
+ * these macros, which use rs = 0 to get the tophys offset in rd, rather than
+ * converting the address in r0, and so this version has to do that too
+ * (i.e. set register rd to 0 when rs == 0).
+ */
 #define tophys(rd,rs)                          \
        addis   rd,rs,0