From mboxrd@z Thu Jan 1 00:00:00 1970 From: linus.walleij@linaro.org (Linus Walleij) Date: Thu, 15 Nov 2012 18:31:43 +0100 Subject: [PATCH 1/2] Boottime: A tool for automatic measurement of kernel/bootloader boot time In-Reply-To: <201211151225.31066.arnd@arndb.de> References: <1352973847-21605-1-git-send-email-lee.jones@linaro.org> <20121115112543.GC21682@gmail.com> <201211151225.31066.arnd@arndb.de> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Thu, Nov 15, 2012 at 1:25 PM, Arnd Bergmann wrote: > On Thursday 15 November 2012, Lee Jones wrote: >> >> > > +/* 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