On Tue, 26 Oct 2010, James Bottomley wrote: > On Tue, 2010-10-26 at 21:29 -0400, John David Anglin wrote: > > > - shared memory --- there is SHMLBA boundary that causes that all > > mappings > > > are aligned to this boundary --- it is **WRONG** in the current > > kernel!!! > > > It is only 4MB and should be 16MB!!! > > > > James has said that the max for all PA-RISC implementations is > > 4 MB. The value is returned by the PDC_CACHE call. Maybe a BUG_ON is > > called for. The alias boundary can be determined by the alias field > > in the D_conf return value. > > Why is it I get blamed for everything cache related on parisc? The You don't get blamed, we're just trying to find bugs :) > statement in the manuals that the equivalency modulus is 16MB was left > for future expansion. However, given PA8900 is the last in the series, > there is no future expansion. John Marvin (I think it was) from the HP > processor group confirmed that the largest equivalency modulus for any > produced parisc processor is 4MB, so that's what we use in the kernel. > > James The largest L2 cache size is 64MB --- so if the cache is 4-way associative, the equivalency distance is 16MB (as the manual says). If the equivalency distance were 4MB, the L2 cache would have to be 16-way (or the cache would have to be physically indexed and you wouldn't have to care about its consistency at all). Mikulas -- To unsubscribe from this list: send the line "unsubscribe linux-parisc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
