From: tndave <[email protected]> Date: Mon, 24 Oct 2016 11:31:14 -0700
> > > On 10/24/2016 10:45 AM, David Miller wrote: >> From: Tushar Dave <[email protected]> >> Date: Mon, 10 Oct 2016 11:12:02 -0700 >> >>> From: Dave Kleikamp <[email protected]> >>> >>> This change allows ATU (new IOMMU) in SPARC systems to request >>> large (32M) contiguous memory during boot for creating IOTSB backing >>> store. >>> >>> Signed-off-by: Dave Kleikamp <[email protected]> >>> Signed-off-by: Tushar Dave <[email protected]> >> >> If you need 32MB allocations, wouldn't a max zone order of 12 be >> sufficient? (8K << 12 == 32MB) > Yes, but config FORCE_MAX_ZONEORDER is actually maximum order plus > one. > For example, a value of 13 means that the largest free memory block is > 2^12 pages. For 32MB we need 2^12 8K pages, hence FORCE_MAX_ZONEORDER > must be MAX_ORDER + 1 i.e. 13. Ok, thanks for explaining.
