Le 16/09/2010 12:18, Wolfgang Wegner a écrit :
On Thu, Sep 16, 2010 at 07:54:03PM +1000, Graeme Russ wrote: [...]
I have a 'cold-boot' parameter which is set by the reset vector code. I can use this to selectively skip 'once-only' initialisation
[...]
I don't doubt that you are entirely correct. But there are many ways to skin a cat. My problem was to reduce the build->burn->boot development time where the burn phase was the longest. The low level boot and device initialisation all works and hasn't changed in quite a while, so I can rely on what is on my (nearly a year) old image.
I see this feature not only nice to speed up development, sometimes it also comes in really handy for production, too - if you have to struggle with debugging tools that are either plain too stupid to program some flash devices or are much slower than U-Boot, you can simply run a specially built version from RAM and/or provide it with an environment in RAM to do all the actual flashing for the board production.
A common framework (within the bounds of cross-architecture limitations) would be nice
For some targets, there may be fragments present in the code when searching for CONFIG_MONITOR_IS_IN_RAM, which statically disables all the low-level initialization to allow U-Boot being loaded from a first-stage loader or debugger. But beware, it is not always functional out-of-the-box.
For ARM926, you can disable low level init stuff and run from RAM by defining CONFIG_SKIP_LOWLEVEL_INIT. This works and is actively used in kirkwood where low level init is done by a previous loader.
(independently you can disable relocation from FLASH to RAM with CONFIG_SKIP_RELOCATE_UBOOT.)
Maybe we could start by standardizing a single (set of) config option(s) for skipping inits and have all boards use that?
Amicalement,