Re: [PATCH v3] riscv: Allow to downgrade paging mode from the command

[Alexandre Ghiti]

Hi Conor,

On 1/23/23 12:53, Conor Dooley wrote:
> Hey Alex,
>
> On Mon, Jan 23, 2023 at 11:48:41AM +0100, Alexandre Ghiti wrote:
> > Add 2 early command line parameters that allow to downgrade satp mode
> > (using the same naming as x86):
> > - "no5lvl": use a 4-level page table (down from sv57 to sv48)
> > - "no4lvl": use a 3-level page table (down from sv57/sv48 to sv39)
> >
> > Note that going through the device tree to get the kernel command line
> > works with ACPI too since the efi stub creates a device tree anyway with
> > the command line.
> >
> > Also, as those params are treated very early in the boot process and we
> > use standard device tree functions that may be kasan instrumented, we
> > only enable them for !KASAN configurations.
> >
> > Reviewed-by: Björn Töpel <bjorn@xxxxxxxxxx>
> > Signed-off-by: Alexandre Ghiti <alexghiti@xxxxxxxxxxxx>
> > ---
> A changelog would be nice here, especially since this is a resend.


I think you may have commented the wrong patch, this one is wrong, hence 
the resend!


> >   .../admin-guide/kernel-parameters.txt         |  9 ++-
> >   arch/riscv/mm/init.c                          | 72 +++++++++++++++++--
> >   2 files changed, 74 insertions(+), 7 deletions(-)
> >
> > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> > index 6cfa6e3996cf..fd647412ec91 100644
> > --- a/Documentation/admin-guide/kernel-parameters.txt
> > +++ b/Documentation/admin-guide/kernel-parameters.txt
> > @@ -3578,8 +3578,15 @@
> >   			emulation library even if a 387 maths coprocessor
> >   			is present.
> >   
> > -	no5lvl		[X86-64] Disable 5-level paging mode. Forces
> > +	no4lvl		[RISCV] Disable 4-level and 5-level paging modes. Forces
> > +			kernel to use 3-level paging instead.
> > +			Note: On RISC-V, this can't be used when KASAN is
> > +			enabled.
> > +
> > +	no5lvl		[X86-64,RISCV] Disable 5-level paging mode. Forces
> >   			kernel to use 4-level paging instead.
> > +			Note: On RISC-V, this can't be used when KASAN is
> > +			enabled.
> >   
> >   	nofsgsbase	[X86] Disables FSGSBASE instructions.
> >   
> For the improved descriptions & commit message:
> Reviewed-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>


Thanks for that, would you mind adding that to the resend patch?

Thanks again,

Alex


> Thanks,
> Conor.
>
>
> _______________________________________________
> linux-riscv mailing list
> linux-riscv@xxxxxxxxxxxxxxxxxxx
> http://lists.infradead.org/mailman/listinfo/linux-riscv