On 06/27/2013 08:36:37 PM, Kevin Hao wrote:
On Thu, Jun 27, 2013 at 02:58:34PM -0500, Scott Wood wrote:
> On 06/26/2013 09:00:33 PM, Kevin Hao wrote:
> >This is based on the codes in the head_44x.S. Since we always
align to
> >256M before mapping the PAGE_OFFSET for a relocatable kernel, we
also
> >change the init tlb map to 256M size.
>
> Why 256M?
For two reasons:
1. This is the size which both e500v1 and e500v2 support.
2. Since we always use the PAGE_OFFSET as 0xc0000000, the 256M is
max alignment value we can use for this virtual address.
0xc0000000 is 1G-aligned, so I don't see why 256M is the maximum (after
verifying that enough memory is present with the right alignment, of
course). The TLB1 savings would probably not be enough to justify
figuring that out, though.
-Scott
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