Re: [Qemu-ppc] [PATCH 7/8] PPC: booke206: Check for min/max TLB entry size

[Alexander Graf]

On 01/23/2012 06:32 PM, Scott Wood wrote:
> On 01/20/2012 10:15 PM, Alexander Graf wrote:
> > @@ -4273,6 +4274,16 @@ void helper_booke206_tlbwe(void)
> >           tlb->mas1&= ~MAS1_IPROT;
> >       }
> >
> > +    /* check that we support the targeted size */
> > +    size_tlb = (tlb->mas1&  MAS1_TSIZE_MASK)>>  MAS1_TSIZE_SHIFT;
> > +    size_ps = booke206_tlbnps(env, tlbn);
> > +    if ((tlb->mas1&  MAS1_VALID)&&  (tlbncfg&  TLBnCFG_AVAIL)&&
> > +        !(size_ps&  (1<<  size_tlb))) {
> > +        helper_raise_exception_err(POWERPC_EXCP_PROGRAM,
> > +                                   POWERPC_EXCP_INVAL |
> > +                                   POWERPC_EXCP_INVAL_INVAL);
> > +    }
> > +
> >       if (booke206_tlb_to_page_size(env, tlb) == TARGET_PAGE_SIZE) {
> >           tlb_flush_page(env, tlb->mas2&  MAS2_EPN_MASK);
> >       } else {
> For tlb0 on e500 and derivatives, tsize is explicitly documented as
> ignored.  Software may rely on this.

Yup, that's why there's the check for TLBnCG_AVAIL, which indicates that 
a TLB has dynamic page size capabilities, which TLB0 does not have.


Alex