[PATCH] powerpc/85xx: allow CONFIG_PHYS_64BIT to be selectable

[Huang Changming-R66093]

> > -----Original Message-----
> > From: Tabi Timur-B04825
> > Sent: Friday, February 24, 2012 10:46 AM
> > To: Li Yang-R58472
> > Cc: Huang Changming-R66093; galak at kernel.crashing.org;
> > benh at kernel.crashing.org; Wood Scott-B07421; linuxppc-dev at ozlabs.org
> > Subject: Re: [PATCH] powerpc/85xx: allow CONFIG_PHYS_64BIT to be
> > selectable
> >
> > Li Yang-R58472 wrote:
> >
> > > I agree with Changming that we shouldn't setting PHYS_64BIT by
> default.
> >
> > The default kernel should always be the compatible with as much as
> > possible.  Disabling PHYS_64BIT by default means that the default
> > kernel will not work with a 36-bit DTS.  If you attempt to boot such a
> > kernel with a 36-bit DTS, there will be no text output.  Most people
> > will not know why it's not working.
> >
> > So the safest option is for PHYS_64BIT to be enabled by default.  That
> > way, the kernel will always work.
> 
> Even though the user still need to know the addressing mode that u-boot
> is using.  It won't work if the addressing mode of u-boot and device tree
> are different.
> 
Yes, u-boot must has the same address mode with DTS, otherwise, we can't boot the kernel.