Lee Schermerhorn <Lee.Schermerhorn@xxxxxx> wrote: > > This patch restores the 64-bit system FLAGS_RESERVED to 32 and > moves the PG_uncached bit back down into the high order byte of > the low order flags word. Yes, that's what the persent version of that patch does (I made it bit 31, so 64-bit-only flags can work their way downwards). It's a bit sad that we're using all 32 of the high-order bits. We might need to revisit that later, if flags get tighter. From: Andrew Morton <akpm@xxxxxxxx> As Nick points out, only ia64 uses PG_uncached. So we can push it up into the higher bits of the lower half of page->flags and make room for another flag on 32-bit machines. Cc: "Luck, Tony" <tony.luck@xxxxxxxxx> Cc: Jesse Barnes <jbarnes@xxxxxxx> Cc: Jes Sorensen <jes@xxxxxxxxxxxxxxxxxx> Cc: Nick Piggin <nickpiggin@xxxxxxxxxxxx> Cc: Andy Whitcroft <apw@xxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxx> --- diff -puN include/linux/page-flags.h~pg_uncached-is-ia64-only include/linux/page-flags.h --- devel/include/linux/page-flags.h~pg_uncached-is-ia64-only 2006-04-09 23:08:43.000000000 -0700 +++ devel-akpm/include/linux/page-flags.h 2006-04-09 23:09:13.000000000 -0700 @@ -7,6 +7,8 @@ #include <linux/percpu.h> #include <linux/cache.h> +#include <linux/types.h> + #include <asm/pgtable.h> /* @@ -88,7 +90,17 @@ #define PG_nosave_free 18 /* Free, should not be written */ #define PG_buddy 19 /* Page is free, on buddy lists */ -#define PG_uncached 20 /* Page has been mapped as uncached */ + +#if (BITS_PER_LONG > 32) +/* + * 64-bit-only flags build down from bit 31 + * + * 32 bit -------------------------------| FIELDS | FLAGS | + * 64 bit | FIELDS | ?????? FLAGS | + * 63 32 0 + */ +#define PG_uncached 31 /* Page has been mapped as uncached */ +#endif /* * Global page accounting. One instance per CPU. Only unsigned longs are - : send the line "unsubscribe linux-ia64" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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