Messages in this thread | | | Date | Thu, 17 Jun 2010 11:35:21 -0700 | From | "H. Peter Anvin" <> | Subject | Re: [PATCH] x86: OLPC: add support for calling into OpenFirmware (v4) |
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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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