Re: [PATCH 1/6] MIPS: Loongson64: Do not write the read only field LPA of CP0_CONFIG3

[Tiezhu Yang]

On 10/30/2020 12:00 PM, Jiaxun Yang wrote:
> 在 2020/10/29 16:02, Tiezhu Yang 写道:
> > The field LPA of CP0_CONFIG3 register is read only for Loongson64, so 
> > the
> > write operations are meaningless, remove them.
> >
> > Signed-off-by: Tiezhu Yang <yangtiezhu@xxxxxxxxxxx>
> > ---
> >   arch/mips/include/asm/mach-loongson64/kernel-entry-init.h | 8 --------
> >   arch/mips/loongson64/numa.c                               | 3 ---
> >   2 files changed, 11 deletions(-)
> Hi Tiezhu,
>
> AFAIK it's not read only on 3A1000.
> Have you check with hardware guys?

Hi Jiaxun,

Yes, I checked it before send this patch,  the field LPA of CP0_CONFIG3
on 3A1000 is also read only,  we can see the related description in the
chapter 3.22 of Loongson_3A1000_cpu_user_2.

And also we can see the following description in the chapter
"9.45 Configuration Register 3 (CP0 Register 16, Select 3)" of
MD00091-2B-MIPS64PRA-AFP-05.04:
"The Config3 register encodes additional capabilities.
All fields in the Config3 register are read-only."

Thanks,
Tiezhu

> Thanks.
>
> - Jiaxun