[PATCH 2/2] powerpc: Make context bits depend on virtual addr size.

[David Laight]

> +#define CONTEXT_BITS		19
> +#define USER_ESID_BITS		18
> +#define USER_ESID_BITS_1T	6
> +
> +/*
> + * 256MB segment
> + * The proto-VSID space has 2^(CONTEX_BITS + USER_ESID_BITS) - 1 segments
> + * available for user + kernel mapping. The top 4 contexts are used for
> + * kernel mapping. Each segment contains 2^28 bytes. Each
> + * context maps 2^46 bytes (64TB) so we can support 2^19-1 contexts
> + * (19 == 37 + 28 - 46).
> + */

I can't help feeling this would be easier to understand if a full
64? 80? bit address was shown with the various bit ranges identified.

Given the comment, I'd have expected CONTEXT_BITS to be calculated
from three other named constants - rather than being set to 19.

	David