first ever Qubes forum post.
I recently got my hands on a new laptop with an Intel Core Ultra 275HX. This (according to Intel documentation) has S3 sleep support. This support relies on the intel_pmc_ssram_telemetry driver which was recently moved out of intel_pmc_core. Without the telemetry driver, core won’t load and i am unable to suspend correctly.
Upon booting with i am greeted with a pretty much invisible error. Sometimes i catch it in the debug messages, other times the screen goes blank right before.
If i understand correctly, the telemetry driver tries to access some page in memory, which does not exist, causing xen to try to update the mappings from the mmu. I am not sure what exactly is responsible for the panic at this point.
All i know is that i need to blacklist the intel_pmc_ssram_telemetry driver for my system to boot correctly. This issue does exist on the stable, devel and latest kernel of qubes and it does not exist on a simple fedora installation with the same kernel versions.
So I am pretty sure it is a xen related issue. I have yet to find any other references to this issue except people saying to just disable that module which sadly is not a workable solution for me.
Any help or ideas would be great because i am slowly running out of things to try.
The failing boot was done using the default qubes and xen parameters and loglevel=8.
The rest of this hardware is great and i would love to get this fixed but i could not find anything useful regarding this problem anywhere online.
I have the same problem on my machine, but simply blacklisting works fine for me. But as I had some time on my hands looked a bit further into this.
It seems that this is a XEN vs direct hardware issue. I’ve found this commit that addresses this issue (or one like it); but it seems it did not carry over to the new driver.
You could start the investigation to see if this pattern appears in the new driver.
Bloged’s Xen-vs-bare-metal read matches what your stacktrace shows. The interesting bit is the xen_mc_flush warning with multicall result -16 right before the page fault on that ffffc900 address. That usually means the telemetry driver is touching MMIO that Xen never mapped into the guest, which is why the same kernel is fine on bare Fedora.
If you need S3 and blacklisting is not acceptable, two practical next steps:
1. Boot with modprobe.blacklist=intel_pmc_ssram_telemetry and check whether intel_pmc_core alone still gives you usable suspend (cat /sys/power/mem_sleep and a short suspend test).
2. File or bump a Xen/Qubes kernel bug with that stacktrace plus lspci -nn -s 00:14.0 and the exact kernel (uname -r). The older pmc_core Xen mmap fix likely needs the same treatment in the new intel_pmc_ssram_telemetry driver.
Meanwhile mem_sleep_default=s2idle can keep the machine usable while that lands, even if battery drain is worse than real S3.