Unable To Read System Registers on AsahiLinux

[adamtuby]

Hey, I've tried writing a very basic kernel module for asahi that exposes EL1 system registers to userspace, but it always fails with reading the system registers as 0. I then found out that even EL0 registers such as CNTPCT_EL0 aren't accessible from EL0, while on the other hand, the preinstalled bare metal macOS on my mac does expose those system registers. Is there some kind of barrier between asahi and the hardware?

Thanks in advance for any type of help/guidance,
Adam.

[marcan]

There is nothing special involved here, other than the Linux kernel not configuring CNTPCT_EL0 as readable by userspace. EL1 system registers are readable from the kernel as you would expect. See CNTKCTL_EL1 for the userspace access config.