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![Nathan Lynch](/assets/img/avatar_default.png)
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>
39 lines
1.4 KiB
C
39 lines
1.4 KiB
C
#ifndef _LINUX_AUXVEC_H
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#define _LINUX_AUXVEC_H
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#include <asm/auxvec.h>
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/* Symbolic values for the entries in the auxiliary table
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put on the initial stack */
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#define AT_NULL 0 /* end of vector */
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#define AT_IGNORE 1 /* entry should be ignored */
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#define AT_EXECFD 2 /* file descriptor of program */
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#define AT_PHDR 3 /* program headers for program */
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#define AT_PHENT 4 /* size of program header entry */
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#define AT_PHNUM 5 /* number of program headers */
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#define AT_PAGESZ 6 /* system page size */
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#define AT_BASE 7 /* base address of interpreter */
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#define AT_FLAGS 8 /* flags */
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#define AT_ENTRY 9 /* entry point of program */
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#define AT_NOTELF 10 /* program is not ELF */
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#define AT_UID 11 /* real uid */
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#define AT_EUID 12 /* effective uid */
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#define AT_GID 13 /* real gid */
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#define AT_EGID 14 /* effective gid */
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#define AT_PLATFORM 15 /* string identifying CPU for optimizations */
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#define AT_HWCAP 16 /* arch dependent hints at CPU capabilities */
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#define AT_CLKTCK 17 /* frequency at which times() increments */
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#define AT_SECURE 23 /* secure mode boolean */
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#define AT_BASE_PLATFORM 24 /* string identifying real platform, may
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* differ from AT_PLATFORM. */
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#define AT_EXECFN 31 /* filename of program */
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#ifdef __KERNEL__
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#define AT_VECTOR_SIZE_BASE 18 /* NEW_AUX_ENT entries in auxiliary table */
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/* number of "#define AT_.*" above, minus {AT_NULL, AT_IGNORE, AT_NOTELF} */
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#endif
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#endif /* _LINUX_AUXVEC_H */
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