[U-Boot] Avoiding reload on ARM U-BOOT

[Marek Vasut <marek.vasut@gmail.com>]

> Hello again
> 
> Sorry for slipping the u-boot list e-mail address
> 
> i understand the benefit of relocating u-boot to the end of DRAM but in
> systems where boot time is critical this redundant copy is undesirable.
> anyway i understand there is no official way of avoiding it.

You can boot linux directly via SPL if your boottime is critical. And, if you do 
not want to boot linux directly, implement some "hit key to interrupt direct 
booting sequence" into SPL.

> 
> One more question i have is regarding the SPL Framework. i read all the
> documentation i could find about the SPL but i don't think i fully
> understand the usage of this framework. since i noticed several SPL Macros
> around the relocation code i suspected it has something to do with
> relocation or u-boot running as secondary boot program

If you can read only a small piece of eg. NAND with your bootrom, you use SPL. 
The purpose is to init the system (ram, gpio ...) and load the u-boot (the big 
bootloader).

M
> 
> i would appreciate a short explanation when CONFIG_SPL or CONFIG_NAND_SPL
> should be set ?
> 
> Thanks again
> 
> Yehuda
> 
> On Fri, Feb 3, 2012 at 10:15 AM, Marek Vasut <marek.vasut@gmail.com> wrote:
> > > Hello Marek
> > 
> > ALWAYS CC U-BOOT ML
> > 
> > > Thank you for your answer
> > > 
> > > My SOC (Marvells Armada Controller) uses a bootrom code to copy to
> > > initialize the DRAM and to copy the u-boot image. so the entire DRAM
> > > init and copy sequence in u-boot is redundant.
> > 
> > I see. I know about this soc's bootrom. Though it still can't place the
> > bootloader properly to the end of DRAM.
> > 
> > > in previous version there was a way to avoid this. i find it limiting
> > 
> > that
> > 
> > > there isn't a way in the new version.
> > > 
> > > Why would i want to relocate the code anyway ?
> > 
> > See above, to place it to the end of DRAM.
> > 
> > > Yehuda
> > > 
> > > On Thu, Feb 2, 2012 at 11:34 AM, Marek Vasut <marek.vasut@gmail.com>
> > 
> > wrote:
> > > > > Hello everyone
> > > > > 
> > > > > im trying to port u-boot 2011-09 to a new board with an arm based
> > > > > SOC
> > > > > 
> > > > > i found that u-boot will always relocate the code even if it is
> > 
> > placed
> > 
> > > > > already in DDR which is the case with my SOC.
> > > > 
> > > > The u-boot is always relocated to the end of the DRAM, which is
> > > > likely what you
> > > > want. And it's quite a quick process. So if you are manufacturing
> > > > your soc with
> > > > various size of RAM, you want the relocation to happen. What SoC is
> > 
> > that
> > 
> > > > anyway?
> > > > 
> > > > > is there any clean way to avoid relocating the u-boot ? does the
> > > > > various SPL configs have something to do with that ?
> > > > 
> > > > Not really and you don't want this to happen.
> > > > 
> > > > M
> > > > 
> > > > > if yes which one should i define ?
> > > > > 
> > > > > Thanks in advance
> > > > > 
> > > > > Yehuda