From: "Tomaž Šolc" <tomaz.solc@klevio.com>
To: Sascha Hauer <s.hauer@pengutronix.de>
Cc: barebox@lists.infradead.org
Subject: Re: [PATCH 3/3] commands: add of_bootargs command.
Date: Fri, 22 Feb 2019 11:38:58 +0100 [thread overview]
Message-ID: <c63c27fe-9e12-e3a2-16b1-279b047bf3a1@klevio.com> (raw)
In-Reply-To: <20190222074922.smfgbcwqmd6uddgi@pengutronix.de>
Hi Sascha,
On 22. 02. 19 08:49, Sascha Hauer wrote:
> On Thu, Feb 21, 2019 at 10:28:48AM +0100, Tomaz Solc wrote:
>> This commit adds an of_bootargs command that extracts a bootargs
>> property from a device tree and saves it to a global variable.
>>
>> For example, a bootloader environment can use this command to extract
>> the bootargs to linux.bootargs.vc, which then gets included into the
>> final bootargs for the kernel using CONFIG_FLEXIBLE_BOOTARGS.
>
> Do we need an extra command for this? Can't you just unflatten the
> VideoCore provided device tree in the board code you have added in 2/3
> and set global.linux.bootargs.vc from there? It seems to be just the
> right thing without further user intervention.
I wanted to keep things flexible. I thought having an explicit command
to import the args into Barebox is better than doing this automatically
in rpi-common.c.
As far as I know [1], upstream kernels use their own device tree and
don't need bootargs and fdt from VideoCore. On the other hand, I'm using
the Raspbian-supplied kernels that do depend on these two things. That's
also why I liked the approach where the VideoCore fdt is saved into a
file, where it can be passed to boot or not, depending on the environment.
If you think of_bootargs is too specific for a command, I can make it
more general and have it save an arbitrary property from a fdt into a
global variable (something similar to readf). That might be useful for
something else as well.
[1]
https://elinux.org/RPi_Upstream_Kernel_Compilation#Building_your_bootloader
Best regards
Tomaž
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next prev parent reply other threads:[~2019-02-22 10:39 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-21 9:28 [PATCH 0/3] VideoCore FDT interop for Raspberry Pi Tomaz Solc
2019-02-21 9:28 ` [PATCH 1/3] ARM: start: save end of memory passed to start Tomaz Solc
2019-02-21 9:28 ` [PATCH 2/3] ARM: rpi: save fdt that was passed from VideoCore Tomaz Solc
2019-02-26 15:18 ` Roland Hieber
2019-02-21 9:28 ` [PATCH 3/3] commands: add of_bootargs command Tomaz Solc
2019-02-22 7:49 ` Sascha Hauer
2019-02-22 10:38 ` Tomaž Šolc [this message]
2019-02-22 11:08 ` Sascha Hauer
2019-02-26 15:21 ` Roland Hieber
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