Hi Stephen,
On Tue, Jan 8, 2013 at 8:42 AM, Stephen Warren swarren@wwwdotorg.org wrote:
On 01/07/2013 08:16 PM, Simon Glass wrote:
Hi,
On Mon, Jan 7, 2013 at 2:21 PM, Curt Brune curt@cumulusnetworks.com wrote:
On 01/07/2013 12:12 PM, Wolfgang Denk wrote:
Dear Curt Brune,
In message 50EB0D92.2020707@cumulusnetworks.com you wrote:
What I would love is to have a single multi-file uImage I could use on all my platforms. The idea is to introduce a new image type that is a list of device tree blobs.
In addition to the file system based approach suggested by Stephen, you should have a look into using FIT images (see doc/uImage.FIT/ ). One of the reasons for creating these was to deal with situations exactly as you describe...
I think that will work perfectly. Thank you for the suggestion.
Note also there is code in mainline now to select the correct FDT from a list of them in a FIT. based on the model name. Then it can pass this to the kernel. So if you have a way of getting the model name in U-Boot, it might just work.
Hmmm. What's the model name compared against? U-Boot board name variable would be nice!
At the moment it compares against the model in the U-Boot FDT (CONFIG_OF_CONTROL). When flashing a board, you pack u-boot.bin with the selected .dtb file containing this model name. Then when U-Boot runs it knows what its model is.
You could do what you describe, but it is then a compile-time check, I think.
There could be other ways to decide on the model name, such as looking at strapping GPIOs, for example:
static const char *detect_model(void) { if (gpio_get_value(36)) return "snow"; else return "flax"; }
As a general comment here, I think the main issue Curt is facing is how to select the correct DT in U-Boot. Whether the n DTBs to be selected between are stored in a single FIT file, or stored in separate *.dtb files, seems pretty irrelevant to that core problem of how to select between them.
FIT selects between them already if you know the model - define CONFIG_FIT_BEST_MATCH and it should work.
Regards, Simon