[U-Boot] Getting started with SPL

[Michal Simek]

Hi

On 04/30/2014 11:32 AM, Heshsham Abdul Basit wrote:
> *HI, *
> 
> 
> *OS:* petalinux <https://github.com/Xilinx/u-boot-xlnx/tree/master-next>

it is not OS - it is just xilinx u-boot repo. And petalinux is using
this repo too.

> 
> *Board:* Xilinx z702 evaluation
> board<http://www.xilinx.com/products/boards-and-kits/EK-Z7-ZC702-G.htm>
> having
> ARM Cortex A9 and FPGA on the zc700 SoC
> 
> * Background:* I observed that first message on the console comes after 1
> second. It is the message from u-boot. Why this was happening? Because I
> had to use a fsbl (first stage boot
> loader)<http://blog.fakultaet-technik.de/development-with-zynq-part-3-build-boot-files/>
> for
> initialization of hardware. I suspected that it is this fsbl that is
> consuming 1 second initializing useless hardware which I will not use at
> all. in fact I am not going to use any fpga bitstream also.

In standard flow there is bootrom -> fsbl -> u-boot.
I have never measured where we are spending time in boot.

> So I am trying to boot my Linux image using uboot-SPL
> method<http://www.denx.de/en/pub/Documents/Presentations/EWC2012_Roeder_Zundel_Fastboot.pdf>
> bypassing
> fsbl.
> 
> The main advantage I can get is perhaps fastest possible boot.

yes. But also keep in your mind that depends on which boot device you are using.
QSPI mode should be the fastest one.

> 
> I found this<https://github.com/Xilinx/u-boot-xlnx/blob/master/doc/README.SPL>
> (README.SPL) document
> that explains how to work with SPL. However I have following question w.r.t
> to the this passage in the document:
> 
> The building of SPL images can be with:
> define CONFIG_SPL
> 
> Because SPL images normally have a different text base, one has to be
> configured by defining CONFIG_SPL_TEXT_BASE. The linker script has to be
> defined with CONFIG_SPL_LDSCRIPT.
> 
> Questions:
> 
> 1- In which file I should define #define CONFIG_SPL and
> CONFIG_SPL_TEXT_BASE?

Just config file - you can just grep code and you will find out that it is
in include/configs/ folder.

> 
> 2-Where is the linker script? Do I need to define CONFIG_SPL_LDSCRIPT in
> the linker script ?

If you want to use private linker script then yes. There is also generic one.

> Source code of SPL enabled u-boot for xilinx board I am using is
> this<https://github.com/Xilinx/u-boot-xlnx/tree/master-next>

yes. I have enabled it by default but for correct function you have to copy
ps7_init.c/h files from your hardware design to be align with your hw design

Thanks,
Michal


-- 
Michal Simek, Ing. (M.Eng), OpenPGP -> KeyID: FE3D1F91
w: www.monstr.eu p: +42-0-721842854
Maintainer of Linux kernel - Microblaze cpu - http://www.monstr.eu/fdt/
Maintainer of Linux kernel - Xilinx Zynq ARM architecture
Microblaze U-BOOT custodian and responsible for u-boot arm zynq platform


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