[U-Boot] [PATCH v2 2/2] cmd: Add 'bcb' command to read/modify/write BCB fields

From: Lukasz Majewski <lukma@denx.de>
To: u-boot@lists.denx.de
Subject: [U-Boot] [PATCH v2 2/2] cmd: Add 'bcb' command to read/modify/write BCB fields
Date: Tue, 21 May 2019 11:22:47 +0200	[thread overview]
Message-ID: <20190521112247.2be00787@jawa> (raw)
In-Reply-To: <20190521091352.GA5680@vmlxhi-102.adit-jv.com>

On Tue, 21 May 2019 11:13:52 +0200
Eugeniu Rosca <erosca@de.adit-jv.com> wrote:

> Hi Lukasz,
> 
> On Tue, May 21, 2019 at 10:02:34AM +0100, Alex Kiernan wrote:
> > On Tue, May 21, 2019 at 9:37 AM Lukasz Majewski <lukma@denx.de>
> > wrote:  
> > >
> > > Hi Alex,
> > >  
> > > > On Mon, May 20, 2019 at 8:23 AM Eugeniu Rosca
> > > > <erosca@de.adit-jv.com> wrote:  
> > > > >  
> > > > > >
> > > > > > Should it default to enabled if avb is used?  
> > > > >
> > > > > I think at this specific moment in time, 'bcb' is orthogonal
> > > > > (meaning it is neither a direct, nor a reverse dependency) to
> > > > > any other Android feature in U-Boot. This could be
> > > > > re-assessed, if platform maintainers start to rely on 'bcb'
> > > > > in their U-Boot environments on regular basis.  
> > > >
> > > > 'bcb' looks like something I'd be interested in, not running
> > > > Android at all... currently I (ab)use the bootcounter to
> > > > communicate between the kernel and U-Boot when I want to force
> > > > a board through recovery,  
> > >
> > > I don't know your exact use case, but wouldn't it be better to
> > > use envs (with redundancy) and fw_setenv / fw_printenv from Linux
> > > user space?
> > >
> > > Now those envs even support setting default values for u-boot (as
> > > there is now separate library used for it). Moreover there is
> > > OE/Yocto's recipe 'u-boot-fw-utils' which can be easily used and
> > > installed.  
> 
> That's a truly constructive suggestion. Nevertheless, I believe this
> would not work in case of CONFIG_ENV_IS_NOWHERE=y, which is how U-Boot
> is built and used by the developers in our organization.

I don't mind to see Android's "bcd" supported in U-Boot (I'm even
happy for it). 

And yes - the CONFIG_ENV_IS_NOWHERE means that one loads the default
envs (created at build time) to RAM for booting.

Just one note (maybe you will find it useful) - it is possible to
specify the default envs from external file:
https://lists.denx.de/pipermail/u-boot/2018-March/323347.html

As we don't have memory to store envs we cannot adjust or pass data via
it.

> 
> > 
> > It's a long story... I'm constrained by historic choices, which
> > makes using the environment problematic. But you're right.
> > 
> > -- 
> > Alex Kiernan  
> 

Best regards,

Lukasz Majewski

--

DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
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