1.0 09 June 2000, Simon Trimmer <simon@veritas.com> Initial release. *************************************************************************** >>> What it does *************************************************************************** The microcode_ctl utility is a companion to the P6 microcode driver written by Tigran Aivazian <tigran@veritas.com>. The utility has two uses: a) it decodes and sends new microcode to the kernel driver to be uploaded to Intel P6 family processors. (Pentium Pro, PII, PIII, Xeon etc) b) it signals the kernel driver to release any buffers it may hold The microcode update is volatile and needs to be uploaded on each system boot i.e. it doesn't reflash your cpu permanently, reboot and it reverts back to the old microcode. *************************************************************************** >>> got an AMD or any non-Intel processor? *************************************************************************** This driver is designed for Intel P6 microprocessors only, it will not work with AMD or any other non-Intel processors as they don't support microcode updates or they support it in a manner different from Intel's specs. *************************************************************************** >>> how to compile the kernel to include support for microcode update *************************************************************************** The microcode driver is a feature of the Linux kernel added to the v2.3 stream in February 2000, it needs to be enabled at compile time and it may be compiled as a module. This utility relates to kernel 2.4.0-test1-ac10 or newer. (microcode driver v1.04+) CONFIG_MICROCODE is in the "Processor type and features" configuration section. Since 2.4.0-test1-ac10 the kernel driver supports regular misc device and devfs. To create the device node on a non-devfs system as root type: # mkdir -p /dev/cpu/ # mknod /dev/cpu/microcode c 10 184 If you are using devfs, then you can either access the driver via regular file /dev/cpu/microcode or via misc characte device /dev/misc/microcode, both of which are created automatically by devfs. *************************************************************************** >>> how to compile it *************************************************************************** The utility has a simple Makefile to compile and install the software; # make gcc -g -Wall -o microcode_ctl microcode_ctl.c # make install mkdir -p /usr/local/bin install -m 755 microcode_ctl /usr/local/bin install -m 644 microcode.dat /etc *************************************************************************** >>> getting Intel microcode *************************************************************************** This package has a file called microcode.dat containing Intel microcode, normally this file will be installed as /etc/microcode.dat Intel P6 microcode updates will be hosted on this utility's web page: http://www.urbanmyth.org/microcode/ *************************************************************************** >>> how to invoke it *************************************************************************** The utility installs by default into /usr/local/bin as microcode_ctl it can be invoked simply as /usr/local/bin/microcode_ctl -f /etc/microcode The utility will print something like: microcode_ctl: writing microcode (length: 98304) microcode_ctl: microcode successfuly written to /dev/cpu/microcode The driver will send messages to the system log (/var/log/messages) like: microcode: CPU1 updated from revision 7 to 14, date=09101999 microcode: CPU0 updated from revision 7 to 14, date=09101999 The driver won't let you downgrade or apply the same microcode as the version it is running, it is also possible that the current version of the microcode does not include one suitable for your processor(s). In these cases the utility will fail with EIO and the driver will print an explanation into the system log. For example, refusal to downgrade the microcode produces this message in the log: microcode: CPU1 not 'upgrading' to earlier revision 14 (current=14) microcode: CPU0 not 'upgrading' to earlier revision 14 (current=14) which was caused by the second invocation of microcode_ctl: # microcode_ctl -f microcode.dat microcode_ctl: writing microcode (length: 98304) microcode_ctl: error writing to '/dev/cpu/microcode' errno=5 (Input/output error) microcode_ctl: there may be messages from the driver in your system log. *************************************************************************** >>> freeing off the internal buffer *************************************************************************** Running the utility with the option -i will signal the driver to release and buffers it may have. It may be used in conjunction with -f if it precedes it. *************************************************************************** >>> updating every system boot *************************************************************************** To update your microcode and free the internal buffer on every system boot you'll need to add a line like the following to /etc/rc.d/rc.local /usr/local/bin/microcode_ctl -if /etc/microcode Simple as that. Problems? Contact either myself at simon@veritas.com or Tigran at tigran@veritas.com *************************************************************************** >>> Special thanks *************************************************************************** o Intel Corporation, for supplying microcode update data and publishing the specifications that enabled us to write microcode driver for Linux. - Simon Trimmer <simon@veritas.com> http://www.urbanmyth.org