Re: [PATCH 1/2] MIPS: Allow MIPS32R2 kernel to run on P5600 and M5150

From: Maciej W. Rozycki
Date: Tue May 30 2023 - 04:03:46 EST

On Mon, 29 May 2023, Jiaxun Yang wrote:

> M5150 and P5600 are two MIPS32R5 kernels, however as MIPS32R5 is
> backward compatible with MIPS32R2 there is no reason to forbid
> M5150 and P5600 on MIPS32R2 kernel.

What problem are you trying to solve? The CONFIG_SYS_HAS_CPU_* settings
denote overall platform's support for the given CPU and have nothing to do
with what architecture level a given kernel has been configured for. You
do need to get the settings right for your platform, just as you do in
2/2, but this 1/2 part looks wrong to me.

NB CPU_4KEC is double-listed as R1 and R2 because early revisions of the
4KEc core were actually R1 before switching to R2, so this CPU can report
either revision.

I don't know why CPU_XBURST is also listed as both R1 and R2, the history
looks convoluted with no explanation. Paul, is the CPU also dual-revision
or is it just a bug and it is supposed to be listed under one ISA revision
only, presumably R2?