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SubjectRe: [PATCH] x86: OLPC: add support for calling into OpenFirmware (v5)

* H. Peter Anvin <hpa@zytor.com> wrote:

> On 06/18/2010 12:42 PM, Andres Salomon wrote:
> > +
> > + /* install OFW's PDE permanently into the kernel's pgtable */
> > + set_pgd(&swapper_pg_dir[OLPC_OFW_PDE_NR], *ofw_pde);
> > + flush_tlb();
> > + early_iounmap(base, sizeof(olpc_ofw_pgd) * PTRS_PER_PGD);
>
> I just realized... this flush_tlb() is actually not necessary since on x86
> it is always legal to go from a less permissive configuration to a more
> permissive, and the initial configuration is "not present" which is
> maximally nonpermissive.
>
> Could you take it out and make sure it still works?

small nit: an optimization barrier would still be needed if the result is
being relied on by the kernel.

Thanks,

Ingo


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