On Thu, Nov 15, 2012 at 1:25 PM, Arnd Bergmann [off-list ref] wrote:

On Thursday 15 November 2012, Lee Jones wrote:

quoted

quoted

quoted

+/* for automatic boot timing testcases */
+#define ATAG_BOOTTIME  0x41000403

Where can I refer this ATAG usage? can you point out the reference URL
or patches?

I assumed this would be in Mainline u-boot, but apparently not.
On closer inspection of the internal ST-Ericsson u-boot, this
functionality appears to be provided by patches which currently
exist as delta. So in essence, the bootloader you use will have
to be patched in a similar way for you to retrieve information
surrounding bootloader boot times.

And there was me thinking it was magic. ;)

And since we're moving away from ATAG on ux500 towards DT, it won't
even work in the future. How essential is this part for the operation
of your code?

To be fun we need some mechanism to pass this info from the
boot loader to the kernel.

I think most bootloaders are already dynamically altering their
device trees to put in things like memory size etc so this would
probably be done the same way: a standard binding like for
everything else, then put the data in there.

I don't know if Lee has a modifiable U-boot to try out such
concepts on though?

Yours,
Linus Walleij