[PATCH][Xenial] UBUNTU: [Config] CONFIG_ARM64_VA_BITS=48

[Tim Gardner]

On 02/01/2016 03:31 PM, dann frazier wrote:
> On Fri, Jan 29, 2016 at 06:23:35PM -0700, dann frazier wrote:
>> On NUMA implementations of Cavium ThunderX, node1 memory addresses start with
>> bit 40 set to 1, and therefore requires >= 41 bits of VA.
>>
>> Since we are using 4K pages, this also means moving from 3 to 4 level page
>> tables. The alternative would be increasing our page size. Upstream supports
>> 16K and 64K pages; 16K pages are not universally supported by ARM64 SoCs.
>>
>> 64K pages are pretty universal, but has issues of it's own:
>>   https://bugs.launchpad.net/skipper/+bug/1522204
> 
> Oops - that should be: http://bugs.launchpad.net/bugs/1520162
> 

That bug makes it sound like we might be opening a can of worms with 64K
pages. Any thoughts on how much carnage this might cause ? Maybe we
should wait until binutils has been adjusted so that 4K applications are
64K aligned ?

rtg
-- 
Tim Gardner tim.gardner at canonical.com