Le 03/09/2022 à 14:36, Michael Ellerman a écrit :
> Because 64-bit Book3S uses pgtable-nop4d.h, the P4D is folded into the
> PGD. So P4D entries are actually PGD entries, or vice versa.
>
> The other way to think of it is that the P4D is a single entry page
> table below the PGD. Zero bits of the address are needed to index into
> the P4D, therefore a P4D entry maps the same size address space as a PGD
> entry.
>
> As explained in the previous commit, there are no huge page sizes
> supported directly at the PGD level on 64-bit Book3S, so there are also
> no huge page sizes supported at the P4D level.
>
> Therefore p4d_is_leaf() can never be true, so drop the definition and
> fallback to the default implementation that always returns false.
Then here as well, you are removing the only architecture which
implements a non 'always false' version of p4d_leaf().
x86 has on that is always false:
#define p4d_leaf p4d_large
static inline int p4d_large(p4d_t p4d)
{
/* No 512 GiB pages yet */
return 0;
}
So, should it be dropped as well and all uses removed from core mm ?
Christophe
