Re: [PATCH] mips/mm: Add page soft dirty tracking

[Paul Cercueil]

Hi Thomas,

Le dim. 26 avril 2020 à 18:54, Thomas Bogendoerfer 
<tsbogend@xxxxxxxxxxxxxxxx> a écrit :
> On Tue, Apr 21, 2020 at 05:15:27PM +0800, Guoyun Sun wrote:
> >  User space checkpoint and restart tool (CRIU) needs the page's 
> > change
> >  to be soft tracked. This allows to do a pre checkpoint and then dump
> >  only touched pages.
> >
> >  Signed-off-by: Guoyun Sun <sunguoyun@xxxxxxxxxxx>
> >  ---
> >   arch/mips/Kconfig                    |  1 +
> >   arch/mips/include/asm/pgtable-bits.h |  8 ++++--
> >   arch/mips/include/asm/pgtable.h      | 48 
> > ++++++++++++++++++++++++++++++++++--
>
> this breaks all 32bit builds where CPU support RIXI, because it 
> overflows
> pgtable_bits.

I think we'd need to make PTEs 64-bit at some point.

We wanted to add support for huge-pages on 32-bit MIPS and faced the 
same issue.

-Paul

> Thomas.
>
> --
> Crap can work. Given enough thrust pigs will fly, but it's not 
> necessarily a
> good idea.                                                [ RFC1925, 
> 2.3 ]