[PATCH 5/5] arm: boot: store ATAGs structure into DT "/chosen/linux,atags" entry

Michael Trimarchi michael at amarulasolutions.com
Fri Nov 27 00:44:51 PST 2015


On Fri, Nov 27, 2015 at 9:38 AM, Pali Rohár <pali.rohar at gmail.com> wrote:
> On Thursday 26 November 2015 12:39:30 Tony Lindgren wrote:
>> Just to explore options.. How about make a minimal device driver that
>> just loads the atags blob from /lib/firmware and then shows it in
>> /proc/atags? Of course some checking on the atags should be done by
>> the driver..
> And who can dynamically create that blob file in /lib/firmware? If
> kernel does not export those atags (somehow) from bootloader, then
> userspace is not able to create that blob... cyclic problem.

Are those atags from bootloader fix or they change device by device. If they
are fixed they can be included in some firmware and get from the disk.


> So no, problem is that bootloader provides via custom atags dynamic
> information like: boot reason (how was device started, by rtc alarm? by
> reboot? by usb charger? by power button?), boot mode (should be enter
> into firmware update mode?, is this normal boot mode?), ... and those
> information are needed for some proprietary software (e.g. firmware
> upgrade/flash) but also by any other open source applications (based on
> usb charger we enter different runlevel -- for just only charging
> device).
> --
> Pali Rohár
> pali.rohar at gmail.com
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