[U-Boot] testing x86 builds on the fly

[Graeme Russ <graeme.russ@gmail.com>]

Hi Mike, Marek,

On 07/08/11 10:54, Graeme Russ wrote:
> Hi Mike, Marek,
> 
> On 07/08/11 09:43, Mike Frysinger wrote:
>> On Sat, Aug 6, 2011 at 05:49, Marek Vasut wrote:
>>> On Saturday, August 06, 2011 01:22:38 PM Mike Frysinger wrote:
>>>> disclaimer: i have like 0 u-boot experience on x86.  but i cant find
>>>> README's in the src to answer my questions.
>>>>
>>>> the PIC support on x86 is finished right ?  so does that mean we can
>>>> take a u-boot.bin, tftp it to a running system into external memory,
>>>> and then boot that on the fly purely for testing purposes ?

A little more explanation...

I did once have full PIC support for x86 when loaded with SDRAM already
initialised - It would figure out were it was loaded in relation to
TEXT_BASE and perform the required adjustments during the relocation
phase). But this functionality was removed when the Cache-As-RAM
implementation was introduced.

[snip]

> Now it would be fairly trivial to add a parameter passed by the 'go'
> command which sets a flag in global data that would tell board_init_f to
> not perform SDRAM init which is on my todo list (see below)

Well I just looked at the code and the warm reset entry point sets
GD_FLG_WARM_BOOT in gd->flags so you could easily bypass SDRAM
initialisation by doing a test in the arch specific dram_init_f()

int dram_init_f(void)
{
	if (gd->flags | GD_FLG_WARM_BOOT)
		return 0;

	...
}

Regards,

Graeme