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authorNathan Lynch <ntl@pobox.com>2008-07-22 04:48:46 +1000
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2008-07-25 15:44:39 +1000
commit483fad1c3fa1060d7e6710e84a065ad514571739 (patch)
tree98c2da31a58c71d1ae9c808bdf232cbbbe060550 /include/linux/auxvec.h
parente9f76354ce83a20c7768ad37caa033f6506b4f96 (diff)
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ELF loader support for auxvec base platform string
Some IBM POWER-based platforms have the ability to run in a mode which mostly appears to the OS as a different processor from the actual hardware. For example, a Power6 system may appear to be a Power5+, which makes the AT_PLATFORM value "power5+". This means that programs are restricted to the ISA supported by Power5+; Power6-specific instructions are treated as illegal. However, some applications (virtual machines, optimized libraries) can benefit from knowledge of the underlying CPU model. A new aux vector entry, AT_BASE_PLATFORM, will denote the actual hardware. For example, on a Power6 system in Power5+ compatibility mode, AT_PLATFORM will be "power5+" and AT_BASE_PLATFORM will be "power6". The idea is that AT_PLATFORM indicates the instruction set supported, while AT_BASE_PLATFORM indicates the underlying microarchitecture. If the architecture has defined ELF_BASE_PLATFORM, copy that value to the user stack in the same manner as ELF_PLATFORM. Signed-off-by: Nathan Lynch <ntl@pobox.com> Acked-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'include/linux/auxvec.h')
-rw-r--r--include/linux/auxvec.h6
1 files changed, 5 insertions, 1 deletions
diff --git a/include/linux/auxvec.h b/include/linux/auxvec.h
index 0da17d14fd13..d7afa9dd6635 100644
--- a/include/linux/auxvec.h
+++ b/include/linux/auxvec.h
@@ -26,9 +26,13 @@
#define AT_SECURE 23 /* secure mode boolean */
+#define AT_BASE_PLATFORM 24 /* string identifying real platform, may
+ * differ from AT_PLATFORM. */
+
#define AT_EXECFN 31 /* filename of program */
+
#ifdef __KERNEL__
-#define AT_VECTOR_SIZE_BASE 17 /* NEW_AUX_ENT entries in auxiliary table */
+#define AT_VECTOR_SIZE_BASE 18 /* NEW_AUX_ENT entries in auxiliary table */
/* number of "#define AT_.*" above, minus {AT_NULL, AT_IGNORE, AT_NOTELF} */
#endif