By: -.- (blarg.delete@this.mailinator.com), September 24, 2021 6:00 pm
Room: Moderated Discussions
Simon Farnsworth (simon.delete@this.farnz.org.uk) on September 24, 2021 2:47 am wrote:
> Out of interest, why does the MIDR_EL1 register when combined with the REVIDR_EL1 register not provide
> enough information to identify the model? These are architectural registers in ARMv8-A, and in theory provide
> enough detail to identify not just the model but also the stepping of the chip you're running on.
Oops, forgot that ARM does all this stuff in EL1, an area I tend to ignore.
But yeah, because of its inaccessibility to usermode, it can be a little problematic. Linux seems to allow a passthrough, but other OSes don't necessarily have the same functionality.
Thanks for pointing that out!
(would also be nice to have a reference of what the values map to as well)
> Out of interest, why does the MIDR_EL1 register when combined with the REVIDR_EL1 register not provide
> enough information to identify the model? These are architectural registers in ARMv8-A, and in theory provide
> enough detail to identify not just the model but also the stepping of the chip you're running on.
Oops, forgot that ARM does all this stuff in EL1, an area I tend to ignore.
But yeah, because of its inaccessibility to usermode, it can be a little problematic. Linux seems to allow a passthrough, but other OSes don't necessarily have the same functionality.
Thanks for pointing that out!
(would also be nice to have a reference of what the values map to as well)