linux-kernel - Re: [PATCH] x86: OLPC: add support for calling into OpenFirmware (v5)

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Message-ID: <4C1BCDD5.5040805@zytor.com>
Date:	Fri, 18 Jun 2010 12:49:41 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Andres Salomon <dilinger@...ued.net>
CC:	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 12:42 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?

	-hpa
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