Re: [DistroKit] [PATCH 5/5] v8a: barebox: add a boot target for fastboot loaded image files

[Johannes Zink <j.zink@pengutronix.de>]

Hi Jan,

On 6/6/23 17:07, Jan Lübbe wrote:
> On Tue, 2023-06-06 at 16:47 +0200, Ahmad Fatoum wrote:
>> On 06.06.23 16:31, Johannes Zink wrote:
>>> This allows to boot a kernel with dtb and initrd entirely from RAM after
>>> loading it via Android Fastboot by simply calling 'boot fastboot'.
>>>
>>> Signed-off-by: Johannes Zink <j.zink@pengutronix.de>
>>> ---
>>>   configs/platform-v8a/barebox-common-defaultenv/boot/fastboot | 7 +++++++
>>>   1 file changed, 7 insertions(+)
>>>
>>> diff --git a/configs/platform-v8a/barebox-common-defaultenv/boot/fastboot b/configs/platform-v8a/barebox-common-defaultenv/boot/fastboot
>>> new file mode 100755
>>> index 000000000000..a06414d582bf
>>> --- /dev/null
>>> +++ b/configs/platform-v8a/barebox-common-defaultenv/boot/fastboot
>>> @@ -0,0 +1,7 @@
>>> +#!/bin/sh
>>> +
>>> +global.bootm.image=/tmp/kernel
>>> +global.bootm.initrd=/tmp/initramfs
>>> +global.bootm.oftree=/tmp/oftree
>>> +
>>> +global.linux.bootargs.dyn.root="rdinit=/sbin/init root=/dev/ram"
>>
>> Isn't rdinit=/sbin/init the default?
> 
> rd=/init is the defaut. root=/dev/ram is not needed, AFAIR, it's for initrd, not
> initramfs.
> 
> Also, we could add a symlink /init -> /sbin/init, which would simplify using
> this initramfs with a bootloaders not passing the correct cmdline.
> 
> Jan

I have tested the different permutations:

+-------------------+---------------+-----------+
| rdinit=/sbin/init | root=/dev/ram | result    |
+===================+===============+===========+
| set               | set           | boots     |
+-------------------+---------------+-----------+
| set               | not set       | boots     |
+-------------------+---------------+-----------+
| not set           | set           | fails [1] |
+-------------------+---------------+-----------+
| not set           | not set       | fails [1] |
+-------------------+---------------+-----------+


[1] kernel panic after
[    2.545914] /dev/root: Can't open blockdev
[    2.546279] VFS: Cannot open root device "ram" or unknown-block(1,0): error -6

Thus, we can drop the root=/dev/ram, as you suggested. Gonna change it in v2.

Johannes


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