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Date: Fri, 18 Jun 2010 13:00:19 -0700 From: "H. Peter Anvin" <hpa@...or.com> To: Ingo Molnar <mingo@...e.hu> CC: Andres Salomon <dilinger@...ued.net>, Andrew Morton <akpm@...ux-foundation.org>, linux-kernel@...r.kernel.org, tglx@...utronix.de, mingo@...hat.com, x86@...nel.org, Mitch Bradley <wmb@...top.org> Subject: Re: [PATCH] x86: OLPC: add support for calling into OpenFirmware (v5) On 06/18/2010 12:56 PM, Ingo Molnar wrote: > > * H. Peter Anvin <hpa@...or.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. > In this case the optimization barrier is implicit at the return from an out of line function. -hpa -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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