UEFI and kernel bug

As mentioned in my previous post, I had trouble installing opensuse 13.1M1 on my UEFI box and that turns out to be due to a kernel “bug”.  I’m not an expert on this problem, but I did have to do some reading on it after running into the problem.

It all starts with the Samsung bricking.  You have perhaps heard of that.  Booting linux with UEFI on some Samsung machines was said to brick them (give them the capabilities of a brick, or destroy their functionality).

It turns out that this was caused by writing too much data to NVRAM.  To prevent this from happening, the kernel developers came up with some code to check that there is plenty of free space in NVRAM before allowing any write.

The problem was that the estimates were too conservative, and they were blocking some ordinary use of NVRAM to store new boot entries.  And that is the bug that I ran into.

There’s a description of the bug >here< by Matthew Garrett.  There are additional comments and links in the discussion of bug 822770.  Or do a web search for

efibootmgr kernel bug

to find discussions elsewhere.

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About Neil Rickert

Retired mathematician and computer scientist who dabbles in cognitive science.

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