[U-Boot] 85xx: MPC8536DS board does not build

[Peter Tyser]

On Mon, 2009-08-10 at 15:27 -0400, Jerry Van Baren wrote:
> Kumar Gala wrote:
> > On Aug 10, 2009, at 1:59 PM, Zang Roy-R61911 wrote:
> > 
> >>
> >>> -----Original Message-----
> >>> From: Kumar Gala [mailto:galak at kernel.crashing.org]
> >>> Sent: Monday, August 10, 2009 13:41 PM
> >>> To: Wolfgang Denk
> >>> Cc: U-Boot-Users ML; Zang Roy-R61911
> >>> Subject: Re: 85xx: MPC8536DS board does not build
> >>>
> >>>
> >>> On Aug 10, 2009, at 1:22 PM, Wolfgang Denk wrote:
> >>>
> >>>> Dear Kumar Gala,
> >>>>
> >>>> In message <0EB7516A-2F14-42F7-
> >>>> A6ED-555ADFAB3105 at kernel.crashing.org> you wrote:
> >>>>>> Allocate more space for U-Boot?
> >>>>> I might turn of BEDBUG as its never been properly enabled on
> >>>>> e500/85xx
> >>>>> platforms.
> >>>> Is there any problem with the bigger image which I don't understand
> >>>> yet? Normally we just move down the TEXT_BASE by a sector,
> >>> and that's
> >>>> it.
> >>> Not specifically, its just that ever 85xx image to date has been
> >>> 512k.  I'm just trying to avoid this being the first one that
> >>> changes
> >>> that historic fact.  Especially since compilers like gcc-4.3 seem to
> >>> be able to fit the size in 512k.
> >> We may have more requirements to support graphic in u-boot.
> >> Sooner and later, the size will exceed 512K. Should we have some plan
> >> for this?
> > 
> > So if we are going to increase the limit from 512k do we go to 768k or  
> > 1M?  (Sector size on the board appears to 128k)
> > 
> > I would also like to know how big the flashes are on some of the other  
> > 85xx boards that u-boot supports.
> > 
> > - k
> 
> Hi Kumar, Roy,
> 
> 512K is pretty big for u-boot (not unheard of, but still...).  Is it 
> really 512K or is it using a full page to hold the boot page (top 4K of 
> memory) and one page for the env (unavoidable):
> 
> +-------------------------------------------------------- 0x1_0000_0000
> | One sector dedicated for the power up page (only using 4K)
> +-------------------------------------------------------- 0x0_F800_0000
> | One sector dedicated for the env
> +-------------------------------------------------------- 0x0_F000_0000
> | Two sectors of u-boot
> +----                                                     0x0_E800_0000
> |
> +-------------------------------------------------------- 0x0_E000_0000
> 
> 
> If that is the case, you can gain a sector (less 4K) by rearranging your 
> memory map:
> +-------------------------------------------------------- 0x1_0000_0000
> | One page (4K) of power up vector, the rest is u-boot
> +----                                                     0x0_F800_0000
> |
> +----                                                     0x0_F000_0000
> | Three sectors (less 4K) of u-boot
> +-------------------------------------------------------- 0x0_E800_0000
> | One sector dedicated for the env
> +-------------------------------------------------------- 0x0_E000_0000
> 
> This also makes reprogramming u-boot nicer because your power up vector 
> and u-boot itself are contiguous.

Hi Jerry,
Currently a sector shouldn't be wasted just for the 4K boot page.  Your
second diagram above is similar to current operation - a chunk of the 4k
bootpage is wasted/unused, but other u-boot code shares the same flash
sector with the 4K boot page.  So a little space may be wasted, but not
too much (ie less than 4K).

Best,
Peter