Hi Stefano,
I need to build two set-ups: 1) SPL + u-boot.img for normal device run out of flash 2) u-boot.imx for initial device load together with fastboot
For (2) SPL + kermit + u-boot.img is not an option for me, simply because it is too slow.
I agree that the u-boot images in case (1) and (2) do not generally have to be identical. However in my case I don't need them to be different.
You are saying that in order to cover my use case(s) I need two defconfigs. Well, ok... But how do I integrate this into Buildroot? For the sake of maintainability, simplification, reducing chance for an error during build I want to have one Buildroot defconfig, run one build command and get all the necessary images. How do I do that with two U-boot defconfigs?
On 02/09/16 23:45, Stefano Babic wrote:
Hi Petr,
On 02/09/2016 20:57, Petr Kulhavy wrote:
Hi,
you have already brought it to the point - it needs two defconfigs. This means double the files in U-boot and second and more important, how does it integrate into a tool like Buildroot? In other words I'm trying to do it with just one defconfig.
Alltogether I want to build 3 files:
- SPL which is started by the RBL
- u-boot.img which is loaded by the SPL from the flash after typing 'c'
or similar on the terminal
- u-boot.imx for an initial load of the board via USB if there is no BL
at all
You are assuming that the two different setups are equivalent: u-boot.ix against SPL + u-boot.img. It is not, and they have very different concepts on the basis of two.
Well, I see it slightly different. There is some core functionality of u-boot, which is the command interpreter, scripting, drivers, etc. And then there is some one-time HW initialization that needs to be done. There are two different ways of doing the HW initialization: either via RBL and DCD, or via SPL. But after the HW is initialized it comes in both cases to the same functionality. Once the u-boot is started it does not see the SPL and it probably doesn't even know how it was loaded. It just assumes that certain HW is initialized in a certain way.
In the end both u-boot.imx and u-boot.img are generated out of the same u-boot.bin, just with different mkimage parameters.
And with imx_usb_loader it is still possible to load the SPL via USB, and via UART, SPL loads u-boot.img - see README.imx6.
That is too slow for my needs.
All these images plus rootfs and kernel should be an outcome of one build in Buildroot.
Since the u-boot.imx is in fact u-boot.img with an extra header
It is not: it is different. If it was just an header, I agree that it is like building the bootloader in several formats. That happens for u-boot.bin and u-boot.img, or u-boot.bin and u-boot.imx.
u-boot.imx has much more as a header: it is contain the DCD tables according to the FSL documentation that it is interpreted by the RBL. This is a static setup, because the DCD table is fixed. The RBL sets the SOC according to the values in the DCD table and has (or it can have) nothing to do with the SPL+u-boot.img built for the same board.
On the other side, SPL does not use DCD at all (it could be, but it is empty), and the setup is done with runtime detection by SPL code. The u-boot.img built together with SPL depends on it, that means it does not set again some parts already set by the SPL. That means you cannot simply exchange u-boot.img or u-boot.imx.
I don't want to exchange them. I want to do the same HW initialization which u-boot expects from SPL in the DCD and out of that create the u-boot.imx, which is then directly loaded without SPL. But currently it is not possible.
Generally, we cannot assume that a u-boot.img, behaves as u-boot.imx: it could be, but it is only luck.
Of course, if I want to use two different vesions of u-boot with different sets of commands and features it makes sense to have two defconfigs. But if I want to use the same functionality why should the make process hinder generating the .img and .imx in the same build process?
Regards Petr