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Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution (or distro for short).

Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name GNU/Linux to emphasize the importance of GNU software, causing some controversy.

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How to check if Zenbleed mitigation(chicken bit) is properly set? (self.linux)

submitted 1 year ago* (last edited 1 year ago) by notme to c/[email protected]

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I'm a newb and ran the recommended mitigation code to set a chicken bit on my processor. After running it there was no indication that it worked. Is there a simple way to use rdmsr to check?

https://lock.cmpxchg8b.com/zenbleed.html#solution

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[–] [email protected] 8 points 1 year ago (1 children)

echo $(($(rdmsr -c 0xc0011029) & (1<<9) ))

Should return 512. You might need a ‘sudo’ before the rdmsr (any permission errors in any of this means it didn’t work). Unfortunately, this needs to be done every time you reboot. The next security update for linux will do this automatically.

[–] notme 4 points 1 year ago* (last edited 1 year ago) (1 children)

Thanks, it works. That's a bit worrying.

Do you think Ubuntu 22.04 will get the security update soon? I got a microcode update today but i think that's only a fix for server cpus and not desktop cpus.

For anyone having permission problems turn off secure boot in order for this to work.

[–] ryannathans 3 points 1 year ago (1 children)

Microcode fixes the issue as of 3 days ago

[–] notme 4 points 1 year ago (1 children)

I thought that was only for Eypc processors with desktop processor fixes coming later this year. The articles are not very clear with what is fixed when.

[–] [email protected] 2 points 1 year ago

I also read that fixes are being released now for the high-end chips, but the desktop fixes will be released significantly later