From mboxrd@z Thu Jan 1 00:00:00 1970 From: siarhei.siamashka@gmail.com (Siarhei Siamashka) Date: Wed, 27 Apr 2011 00:53:44 +0300 Subject: Runtime CPU features detection on ARM (/proc/cpuinfo vs. /proc/self/auxv) Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi All, Is the format of /proc/cpuinfo stable and guaranteed to remain the same in the future versions of the linux kernel? I did a bit of searching over the mailing lists and [1], [2] suggest that it is highly likely. I apologize if I missed something and this question is supposed to have been already answered, but I still would like to have a clear confirmation just in case. Additionally, the most authoritative source of information preferably would be some text file under 'Documentation/arm' directory in the linux kernel sources, formally describing /proc/cpuinfo format as needed for the automated parsers. At least one more alternative for detecting cpu features is to use AT_HWCAP from ELF auxiliary vector. But unfortunately it turned out to have some practical issues with qemu-user [3] and valgrind [4]. Using /proc/cpuinfo also provides more information about the cpu type and its revision, which could be used to get more performance for each particular cpu variant and avoid hardware bugs. Looks like 'Features', 'CPU implementer', 'CPU architecture', 'CPU variant', 'CPU part' and 'CPU revision' have more or less complete set of information about the processor for userspace applications. Or maybe somebody can suggest a better method for runtime CPU features detection? Thanks. 1. http://lists.arm.linux.org.uk/lurker/message/20090226.082730.69926605.en.html 2. http://lists.arm.linux.org.uk/lurker/message/20091112.221307.62810e83.en.html 3. http://comments.gmane.org/gmane.comp.graphics.pixman/733 4. http://bugs.kde.org/show_bug.cgi?id=253519 -- Best regards, Siarhei Siamashka