On Wed, Nov 26, 2025 at 04:14:19PM +0000, Mike Leach wrote:
[...]
The key to this is not the questions we are asked, but which platforms are still supported by the linux kernel.
The ETMv3 driver supports both ETMv3 and PTM trace (the programming model is the same, even if the trace decode is vastly different).
So as long as there are platforms supported that use either of those, we need to keep the driver in.
We're not running tests though, so if we find out it's fundamentally broken somehow it could be another justification to remove it, even if the kernel supports the devices. Do you have a board that you can test on Mike?
Don't have one myself, but I believe the TC2 was used in development, (that's the A15/A7 32 bit part - not total compute!) which somewhat conveniently had both etmv3 and ptm trace.
If ETMv4 can be used by Armv7 (arm32) CPUs, and nowdays if Armv7 + ETMv4 is a popular design, it makes sense for me to remove ETMv3 driver.
If Armv7 CPUs are always bound to ETMv3 / PTM, then we should keep the driver.
Thanks, Leo