Monday, October 11th 2021

Update for "Yet Another Hardware Trainwreck" Lands in Linux Kernel as an Urgent Fix for x86 Processors

The x86 instruction set architecture has experienced many issues, and today's announcement is no exception. Yesterday morning, the Linux kernel received an urgent set of patches that are supposed to fix "yet another hardware trainwreck," as Thomas Gleixner, the kernel developer, describes. This time, the problem occurs with the high precision event timer (HPET) that stops once x86 processors reach PC10 idle state. In that event, the timer stops even when the OS/kernel uses it and could potentially cause a vulnerability inside a processor that an attacker can exploit. The problem has been known for quite a while since, in 2019, the Linux kernel started removing HPET functionality from some Intel processors.

The priority of this patch for Linux Kernel version 5.15-rc5 is high and marked as an urgent update. A reliable hardware timer and an interrupt are a must for the proper function of a processor. The hardware fix for this will not happen soon, so the Linux kernel has to adapt to it and create a solution at the software level. According to Mr. Gleixner, "The probability that this problem is going to be solved in the forseeable future is close to zero, so the kernel has to be cluttered with heuristics to keep up with the ever growing amount of hardware and firmware trainwrecks. Hopefully some day hardware people will understand that the approach of "This can be fixed in software" is not sustainable. Hope dies last..."
Sources: Linux Kernel Mailing List, via Phoronix
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7 Comments on Update for "Yet Another Hardware Trainwreck" Lands in Linux Kernel as an Urgent Fix for x86 Processors

#1
ZoneDymo
I sense a tiny whiff of frustration
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#2
XiGMAKiD
From the source "...because some incredibly smart hardware decides to turn off the HPET timer in a low power state - who cares if the OS is relying on it..." and also they believed it's a firmware issue than a hardware problem
Posted on Reply
#3
qubit
Overclocked quantum bit
Such a shame how all these things get exploited by criminals.

I remember in the old days, 80s and 90s, operating systems were open and a skilled programmer could hack them to create lots of cool demos and functions. This included programming the hardware directly, eg the video chip (there was no GPU then). That's all gone now as hardware and software are locked down like Fort Knox against criminal hackers. Big shame. :ohwell:
Posted on Reply
#4
VulkanBros
My friend Mr. Robot would like to have a look at this.....:rolleyes:

On the serious side - I don't think that this, will ever happen:
Hopefully some day hardware people will understand that the approach of "This can be fixed in software" is not sustainable. Hope dies last..."
Posted on Reply
#5
lynx29
ZoneDymoI sense a tiny whiff of frustration
I love the last sentence, "Hope dies last..."

:roll:
Posted on Reply
#6
chrcoluk
I expect the software fix adds bloat, causes slowdown, which in turn drives the demand for faster cpus, which increases sales, hence no hardware fix.
Posted on Reply
#7
Jism
chrcolukI expect the software fix adds bloat, causes slowdown, which in turn drives the demand for faster cpus, which increases sales, hence no hardware fix.
It requires a complete refresh of the line-up.
Posted on Reply