[PATCH] Pass barebox version to kernel

[Peter Mamonov]

On Tue, Feb 27, 2018 at 09:34:30AM +0100, Sascha Hauer wrote:
> Hi Peter,
> 
> On Mon, Feb 26, 2018 at 01:12:02PM +0300, Peter Mamonov wrote:
> > Hi, Sasha,
> > 
> > On Mon, Feb 26, 2018 at 09:23:49AM +0100, Sascha Hauer wrote:
> > > When userspace is interested in the barebox version it has currently no
> > > way of reliably reading it. Add it to the kernel command line as it's an
> > > established way to pass information from the bootloader to the kernel.
> > > If CONFIG_FLEXIBLE_BOOTARGS is enabled then the barebox version is
> > > passed in the "bootloader.version=" variable.
> > 
> > Some time ago we solved a similar problem: a number of parameters including 
> > barebox version, MAC address (which may be random due to the lack of a NIC 
> > EEPROM) and some vendor specific parameters are passed to the kernel via DTB.  
> > A dedicated command was implemented which can either patch the existing DTB or 
> > generate an overlay DTB.  In the latter case the overlay DTB is passed to the 
> > kernel with the help of a new `bootm` option. Of course the latter approach 
> > requires support on the kernel side.
> 
> We could of course pass the barebox version in the /chosen node. That
> would require a of_register_fixup(). Why would we need an extra command
> for that?

Well, it allows some extra flexibility: either original DTB is patched or a
separate DTB blob is generated. However there is no strict need for a command.

My actual point is that passing various bootloader stuff to a kernel via DTB
feels like a cleaner solution, rather than using kernel cmdline for that
purpose.

Regards,
Peter

> The MAC address should already be inserted into the kernel device tree
> automatically.
> 
> Sascha
> 
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