[PATCH] ARM: Versatile Express: Add default memory layout

[Catalin Marinas]

On Thu, 2010-07-22 at 12:30 +0100, Russell King - ARM Linux wrote:
> On Thu, Jul 22, 2010 at 12:19:56PM +0100, Catalin Marinas wrote:
> > On Thu, 2010-07-22 at 12:16 +0100, Russell King - ARM Linux wrote:
> > > The kernel boot requirements document has for the last _8_ years said:
> > >
> > >    The boot loader must pass at a minimum the size and location of the system
> > >    memory, and root filesystem location. Therefore, the minimum tagged list
> > >    should look:
> > >
> > >            +-----------+
> > >    base -> | ATAG_CORE |  |
> > >            +-----------+  |
> > >            | ATAG_MEM  |  | increasing address
> > >            +-----------+  |
> > >            | ATAG_NONE |  |
> > >            +-----------+  v
> > >
> > > and still u-boot gets it wrong...  Now tell me why I hate boot loaders
> > > soo much.
> >
> > Maybe it's time to ignore all boot loaders and do everything in the
> > kernel :)
> 
> Maybe, but then we can never do things like pass command line arguments
> to the kernel, or discover where system RAM is, etc.

I should have rephrased/clarified 'ignore'. It's more like ignoring
incomplete information coming from the bootloader and using sane
defaults in the kernel.

Anyway, I don't think it's worth arguing much here, we've been living
with this issues for many years.

> It's also an argument for avoiding DT!  If boot loaders can't even get
> the most basic of information right...

With DT I see it as slightly different. The DT information is provided
by the board manufacturer and the boot loader doesn't need to do much
discovery. It can be a pretty dumb boot loader just passing the relevant
DT address to the kernel. But that's another thread of discussion (which
unfortunately I didn't have time to follow properly).

-- 
Catalin