Re: [PATCH] sparc64: swapper_tsb and swapper_4m_tsb phys correction

[Bob Picco <bpicco@meloft.net>]

David Miller wrote:	[Tue Sep 16 2014, 09:48:03PM EDT]
> From: Bob Picco <bpicco@meloft.net>
> Date: Tue, 16 Sep 2014 12:50:39 -0400
> 
> > From: bob picco <bpicco@meloft.net>
> > 
> > For physical address larger than 47 bits the computed physical address
> > was insufficient within KERN_TSB_LOOKUP_TL1. This resulted in a vmlinux
> > loaded above 47 bits of physical address unable to boot in spectacular
> > ways.
> > 
> > For now we've expanded the physical address range to 52 bits at the cost of
> > two instructions. Older sparc64 incur two nop-s.
> > 
> > The two new instructions from this patch and the former KTSB_PHYS_SHIFT can
> > potentially be eliminated using memblock aligning large and constraining
> > the physical limit. Essentially use the "sethi" for a physical manipulated
> > address and replacing the "or" at patch time with a "sllx". This would leave
> > the tsb within head_64.S unused and possibly not a good solution for Cheetah+.
> > We'll comtemplate this more in another round.
> > 
> > Cc: sparclinux@vger.kernel.org
> > Signed-off-by: Bob Picco <bob.picco@oracle.com>
> 
> Bob, thanks for doing this work to support up to 49-bits of physical
> addressing.
You are very welcome.
> 
> There are a lot of tradeoffs and thorny issues involved here, so I'm
> going to take some time reviewing this set of patches.
Indeed many tricky issues. I took a first stab at it.
> 
> I'll try to get back to you on these changes in a reasonable amount of
> time, thanks for your patience.
No hurry and thanx.