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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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