Hello James, On 07/12/2016 06:35 PM, Cownie, James H wrote:
The getauxval(3) man page describes the result for AT_HWCAP as "A pointer to a multibyte mask of bits", however the actual value returned is not a pointer, but simply the first 32 bits of the capabilities mask. This can be observed directly. Note the value shown for AT_HWCAP is a 32 bit value that is not a pointer (see AT_PHDR or AT_RANDOM for how pointers are shown).
Thanks! Patch applied. Cheers, Michael
% LD_SHOW_AUXV=1 cat < /dev/null AT_SYSINFO_EHDR: 0x7fffe89fe000 AT_HWCAP: bfebfbff AT_PAGESZ: 4096 AT_CLKTCK: 100 AT_PHDR: 0x400040 AT_PHENT: 56 AT_PHNUM: 9 AT_BASE: 0x0 AT_FLAGS: 0x0 AT_ENTRY: 0x402634 AT_UID: 515 AT_EUID: 515 AT_GID: 114 AT_EGID: 114 AT_SECURE: 0 AT_RANDOM: 0x7fffe8917be9 AT_EXECFN: /usr/bin/cat AT_PLATFORM: x86_64 --- PATCH --- diff --git a/man3/getauxval.3 b/man3/getauxval.3 index 85d7f41..7ce0237 100644 --- a/man3/getauxval.3 +++ b/man3/getauxval.3 @@ -101,12 +101,13 @@ performed by the kernel. The real group ID of the thread. .TP .BR AT_HWCAP -A pointer to a multibyte mask of bits whose settings +A four byte long bit-mask whose settings indicate detailed processor capabilities. The contents of the bit mask are hardware dependent (for example, see the kernel source file .IR arch/x86/include/asm/cpufeature.h -for details relating to the Intel x86 architecture). +for details relating to the Intel x86 architecture; the value +returned is the first 32 bit word of the array described there). A human-readable version of the same information is available via .IR /proc/cpuinfo . .TP --- END PATCH --- -- Jim James Cownie <james.h.cownie@xxxxxxxxx> SSG/DPD/TCAR (Technical Computing, Analyzers and Runtimes) Tel: +44 117 9071438 --------------------------------------------------------------------- Intel Corporation (UK) Limited Registered No. 1134945 (England) Registered Office: Pipers Way, Swindon SN3 1RJ VAT No: 860 2173 47 This e-mail and any attachments may contain confidential material for the sole use of the intended recipient(s). Any review or distribution by others is strictly prohibited. If you are not the intended recipient, please contact the sender and delete all copies.
-- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/ -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
