Subject: Re: [PATCH 1/2] powerpc: enable the relocatable support for the fsl booke 32bit kernel

From: Scott Wood <[email-masked]>
Date: Thu, 27 Jun 2013 20:52:20 -0500

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 =20
> align to
> > >256M before mapping the PAGE_OFFSET for a relocatable kernel, we =20
> also
> > >change the init tlb map to 256M size.
> >
> > Why 256M?
>=20
> 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 =20
verifying that enough memory is present with the right alignment, of =20
course).  The TLB1 savings would probably not be enough to justify =20
figuring that out, though.

-Scott=