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From: H. Peter Anvin on 17 Jun 2010 14:40
On 06/16/2010 07:32 PM, Andres Salomon wrote:
>
> Add support for saving OFW's cif, and later calling into it to run OFW
> commands. OFW remains resident in memory, living within virtual range
> 0xff800000 - 0xffc00000. A single page directory entry points to the
> pgdir that OFW actually uses, so rather than saving the entire page
> table, we grab and install that one entry permanently in the kernel's
> page table.
>
> This is currently only used by the OLPC XO.
>

OK, down to the nitpick level...

> +
> +/* page dir entry containing OFW's pgdir table; filled in by head_32.S */
> +pgd_t *olpc_ofw_pgd __initdata;
> +

This is a physical address, not a pointer. As such it should be
physaddr_t or u32.

> +static DEFINE_SPINLOCK(ofw_lock);
> +
> +#define MAXARGS 10
> +
> +void __init setup_olpc_ofw_pgd(void)
> +{
> + pgd_t *base, *pde, *ofw_pde;
> +
> + if (!olpc_ofw_cif)
> + return;
> +
> + /* fetch the kernel's current PDE */
> + base = __va(read_cr3());
> + pde = &base[OLPC_OFW_PDE_NR];
> +

Since you're touching this so early, you already know that you're
manipulating swapper_pg_dir. If you *didn't* know that, the above code
would be wrong, since the change you're about to make wouldn't propagate
to other kernel tasks.

So just use swapper_pg_dir[OLPC_OFW_PDE_NR] directly.

-hpa
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Prev: Intel MID platform battery driver. (right patch this time)
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