[mythtv-users] My upgrade from Mythbuntu 10.10 to 12.04

Raymond Wagner raymond at wagnerrp.com
Sun Feb 23 17:44:28 UTC 2014


On 2/22/2014 7:38 PM, Will Dormann wrote:
> On 2/22/14, 6:10 PM, Karl Dietz wrote:
>> Its not only about having less then 2^32bytes of memory...
>>
>> http://en.wikipedia.org/wiki/X86-64#Architectural_features
>
> Ah, I wonder if perhaps x32 <http://en.wikipedia.org/wiki/X32_ABI> is
> perhaps the best architecture for MythTV?  More registers, but without
> the application bloat.

No.  The "best" architecture to run is the one most people are running 
(amd64).  Regardless of any specific advantages one special architecture 
may provide, the most popular one is going to have the most developers 
maintaining it, and the most eyes on it to discover bugs.  The only 
counter to this is when you are using some custom application designed 
specifically for one architecture.

The specific issue you are having is because the kernel only allocates a 
limited amount of memory to certain operations, because on a 32-bit 
system, there is a meaningful limitation on the amount of virtual 
address space that can be used.  i686 does have access to more memory 
through paging, but paging can only be used for certain purposes.  Think 
of DOS base memory versus extended memory.  This is not an issue on 
amd64, because the larger address space allows the kernel to play fast 
and loose with allocations in the virtual space, and map that to 
physical memory as it sees fit, even if you only have 2GB of physical 
memory.  The correct fix for this issue on any 64-bit capable CPU is to 
run a 64-bit OS.  Honestly, the correct fix for any non-64-bit capable 
CPU is to finally get around to upgrading.


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