Linux 4.15 Is A Huge Update For Both AMD CPU & Radeon GPU Owners

[Mez']

Hence mainline kernel daily builds (.deb) now include it, right?

After installing it, it very well seems like it. Now waiting for rc1. Hopefully the suspend/resume issue will be solved by the last rc.

[R41N3R]

I'm affected as well by random crashes, sometimes directly after boot. Thought it must be an issue with my AMD GPU, but didn't have the time to figure out what was going wrong. Good to know I'm not the only one! And hope this will be fixed soon, this bug is really bad for Ryzen and Linux.

[xpander]

i was wondering why my screens went black, but the computer was on and couldnt connect to ssh either. that explains. i disablec C6 from bios, seems fine so far. i dont use those boost clocks anyway since i have OC on my cpu. This happened rarely though i even had 6 days uptime, but sometimes i got black screen right after 20 minutes of reboot or similar.

[LeJimster]

i was wondering why my screens went black, but the computer was on and couldnt connect to ssh either. that explains. i disablec C6 from bios, seems fine so far. i dont use those boost clocks anyway since i have OC on my cpu. This happened rarely though i even had 6 days uptime, but sometimes i got black screen right after 20 minutes of reboot or similar.

I've been using disable c-state to prevent random reboot's on my Ryzen 7 1700, I presume we are all experiencing the same issue on Ryzen. It's not ideal long term if we are losing a low power saving mode however.

[xpander]

I've been using disable c-state to prevent random reboot's on my Ryzen 7 1700, I presume we are all experiencing the same issue on Ryzen. It's not ideal long term if we are losing a low power saving mode however.

it still goes down to 0.9V and 1.9ghz (1.9ghz to 2.2 ghz in ondemand mode), so i dont think we loose much. C6 state is something else i guess, for boost state or similar

[LeJimster]

it still goes down to 0.9V and 1.9ghz (1.9ghz to 2.2 ghz in ondemand mode), so i dont think we loose much. C6 state is something else i guess, for boost state or similar

I thought C6 was ultra low power state and C0 highest boost state? Maybe I was misreading. It's not a great experience out of the box for Ryzen users eitherway. I plan to use P-state overclocking eventually, just been working on making sure my system is stable first.

[xpander]

I thought C6 was ultra low power state and C0 highest boost state? Maybe I was misreading. It's not a great experience out of the box for Ryzen users eitherway. I plan to use P-state overclocking eventually, just been working on making sure my system is stable first.

i dont have 100% answer for that but i havent seen ultra low power state with C6 turned on, so i dont know what it is.
My motherboard Asus X370 prime has some bugs with P-state overclocking so i wont touch that i just pushed with voltage offset. 3.9ghz and +0.0275 or something. this way its been stable except the C6 bug with kernel 4.13+.

[xiando]

Did anyone escalate the matter to Linus?

No. It does not seem to be anyone higher up the chain in kernel development or AMD who's aware of this.

As for kernel commit 3fc5b3b6a80b2e08a0fec0056208c5dff757e547, that's not it unless it would somehow trigger something in combination with a lot of other things. I say this because that's a patch that went into 4.12 rc2. Kernels 4.12 will work just fine on Fedora and other distributions who ship with kernels configured with CONFIG_RCU_NOCB_CPU_ALL=Y. Kernel 4.13 and later hangs because this kernel configuration option is removed. The IBM assets commit 44c65ff2e3b0b48250a970183ab53b0602c25764 removed this option which is why kernels later than 4.12 are unusable with Ryzen CPUs without adding a boot parameter.

Adding a boot parameter isn't a good solution. My old mother doesn't know how to do that. You can't expect her to configure her kernel options or find out that she needs one to not make her computer hang for that matter; all people who can barely work a TV remote on their own will know is that their computer stopped working for some reason. And that's the situation, you use Ryzen, you update your kernel and now you're totally screwed.

[LeJimster]

Adding a boot parameter isn't a good solution. My old mother doesn't know how to do that. You can't expect her to configure her kernel options or find out that she needs one to not make her computer hang for that matter; all people who can barely work a TV remote on their own will know is that their computer stopped working for some reason. And that's the situation, you use Ryzen, you update your kernel and now you're totally screwed.

Yep, and for that matter even those with technical expertise might not know about this "fix" that you've found. I certainly didn't until you mentioned it. It needs addressing before Ravens Ridge is released especially. (Presuming the bug occurs on those chips too).

[RavFX]

No. It does not seem to be anyone higher up the chain in kernel development or AMD who's aware of this.

As for kernel commit 3fc5b3b6a80b2e08a0fec0056208c5dff757e547, that's not it unless it would somehow trigger something in combination with a lot of other things. I say this because that's a patch that went into 4.12 rc2. Kernels 4.12 will work just fine on Fedora and other distributions who ship with kernels configured with CONFIG_RCU_NOCB_CPU_ALL=Y. Kernel 4.13 and later hangs because this kernel configuration option is removed. The IBM assets commit 44c65ff2e3b0b48250a970183ab53b0602c25764 removed this option which is why kernels later than 4.12 are unusable with Ryzen CPUs without adding a boot parameter.

Adding a boot parameter isn't a good solution. My old mother doesn't know how to do that. You can't expect her to configure her kernel options or find out that she needs one to not make her computer hang for that matter; all people who can barely work a TV remote on their own will know is that their computer stopped working for some reason. And that's the situation, you use Ryzen, you update your kernel and now you're totally screwed.

Funny how it was removed in the merge windows two week after it was posted on google about being an important Ryzen workaround. For an option that was there for more that five years, what do we call that? an extremely well timed coincidence?

Some people just say to disable C6, that is not the fix. C6 disabled make my system consume an extra 20W of power and I still get display corruption. CONFIG_RCU_NOCB_CPU_ALL Fix everything and allow CPU voltage to go down to 0.4V when IDLE.