June 14, 2020

It would also probably be a good idea to enforce validation of the microcode before sending it to the CPU in kernel mode. There you have it. In this case, the only reason to use devfs is that a regular file has an attribute that device special files do not — the size of the file. Contact your system manufacturer for support and remediation of this system. If I am reading the specter-meltdown-checker correctly it looks like I am not-vulnerable across the board?

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The fixes already in the kernel are better and they don’t use the microcode stuff. Note Be aware that injecting the microcode update directly into the motherboard firmware which might sounds tempting might result in CPU0 being updated but the rest of the CPUs or CPU cores in a multi-core system being left at their initial revision which might cause more problems than running them all at the same initial version. Find More Posts by mralk3.

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microcode_ctl (8) – Linux Man Pages

Just check the microcode revision before and after the changes. Why I posted this: The only work left for user space is to convert the microcode from the format supplied by Intel to one that is easier to manipulate in the kernel and to control the kernel driver via the ioctl 2 system call. All times are GMT Coal Township PA Distribution: The former approach is used by the cpuid and msr Linux drivers. And, since most stock motherboard firmware has some microcode updates even in their initial release versionsit’s probably a good enough reason for everybody to make sure their kernel tries to update all CPUs and cores to the same version so, let this update driver running even if the kernel has the same version which is stored in the motherboard firmware.


It is also possible and quite common to have the BIOS apply a microcode update to some microxode level and later have the OS upgrade it to a newer revision. The path to the microcode is relative to the xen. How does one query if the CPU already has microcode, and what version it is? A set of fixes including Pentium 4 support has been sent by the author to Alan Cox and are likely to go into the official 2.

These structures are initialized at boot time. Obviously, any device driver needs some user space program to interact with it, even if ia3-2 is one of the existing programs like dd 1 or cat 1.

It may contain bug-fixes, general updates, and improvements to some part of the CPU’s built-in code. The function then iterates through the array of struct microcode elements, which updqte copied from the user, and compares the values of the signature and processor flags with those of the current CPU.


The root initramfs goes second separated by space. I tried out the Microcode update driver for my 2. All times are GMT Rebuild and install the kernel as usual.

Intel IA32 Microcode Update Utility

By joining our community you will have the ability to post topics, receive our newsletter, use the advanced search, subscribe to threads and access many other microdode features. This feature is applicable to both single-processor and multi-processor SMP systems. It was tested with Linux 4.

With all this in mind we can now proceed to the much more interesting issues of the actual device driver design and implementation. So, code like this:.

quick tip – microcode updating – undocumented features

Is it Worth It? Mcirocode system is vulnerable. What should I choose? Also, there can be no readers if there is a process writing or issuing ioctl requests. Warning Modules do not work for early microcode, so make sure microcode loading is built-in. Originally Posted by kjhambrick.

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