>> I don't think I remember a restriction here, at least not below 44 bits >> (that's where pfn-s would need to become 64-bit wide). > >The i386 mm code only supports 4 entries in the PGD, so more than 36bit cannot >be mapped right now.
That has nothing to do with the number of physical address bits. >Also even 64MB barely works (many boxes don't boot), you would likely >need at least the 4:4 patch to go >64GB. Also we know there are tons >of possible deadlocks in various subsystems when the lowmem:highmem ratio >gets so out of hand. > >Ok it could be probably all fixed with some work (at least the mm part, >the deadlocks would be more tricky), but would seem fairly >pointless to me because all machines with >36bits support are 64bit capable. That's a different story, and certainly a limiting factor. But this shouldn't e.g. disallow (hypothetical?) systems that have a very sparse memory map extending beyond 64G. Jan - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
