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Date: Fri, 27 Nov 2015 09:44:51 +0100
Message-ID: <CAOf5uwn_3gY=xE8gBS2hZ-O4ZBZruxYRN8a_hO0bqCHy-yA2Gg@mail.gmail.com>
Subject: Re: [PATCH 5/5] arm: boot: store ATAGs structure into DT
 "/chosen/linux,atags" entry
From: Michael Trimarchi <michael@amarulasolutions.com>
To: =?UTF-8?Q?Pali_Roh=C3=A1r?= <pali.rohar@gmail.com>
Cc: Tony Lindgren <tony@atomide.com>, Frank Rowand <frowand.list@gmail.com>,
        Arnd Bergmann <arnd@arndb.de>, Pavel Machek <pavel@ucw.cz>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
        Russell King - ARM Linux <linux@arm.linux.org.uk>,
        Laura Abbott <lauraa@codeaurora.org>,
        Grant Likely <grant.likely@linaro.org>,
        Rob Herring <robherring2@gmail.com>, Will Deacon <will.deacon@arm.com>,
        Ivaylo Dimitrov <ivo.g.dimitrov.75@gmail.com>,
        Sebastian Reichel <sre@debian.org>,
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Hi

On Fri, Nov 27, 2015 at 9:38 AM, Pali Rohár <pali.rohar@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.

Michael

> 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@gmail.com
> --
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