Re: [PATCH 0/6] Expose RPi4'd bootloader configuration

[Nicolas Saenz Julienne]

Hi Rob, thanks for having a look at this.

On Tue, 2020-12-15 at 13:54 -0600, Rob Herring wrote:
> On Tue, Dec 15, 2020 at 1:01 PM Nicolas Saenz Julienne
> <nsaenzjulienne@xxxxxxx> wrote:
> > 
> > Hi Catalin,
> > 
> > On Tue, 2020-12-15 at 18:44 +0000, Catalin Marinas wrote:
> > > On Tue, Dec 15, 2020 at 04:56:20PM +0100, Nicolas Saenz Julienne wrote:
> > > > Soon to be released versions of RPi4's firmware will take of care
> > > > passing their bootloader's configuration to the OS by copying it into
> > > > memory and creating a reserved memory node in the board's DT. In order
> > > > to make use of this information, this series introduces a new generic
> > > > nvmem driver that maps reserved-memory nodes into nvmem devices.
> > > > 
> > > > An alternative approach, less nice IMO, would be to create a
> > > > platform-specific 'soc' driver.
> > > 
> > > What kind of information is this and how would the kernel use it?
> > 
> > Sorry, I wasn't clear enough, the ultimate goal is to use this information from
> > user-space, through nvmem's sysfs interface. The kernel itself has no use for
> > it.
> 
> That still leaves the first question.

It's the bootloader configuration, stuff like boot order, TFTP IP, etc... See
more here:
https://www.raspberrypi.org/documentation/hardware/raspberrypi/bcm2711_bootloader_config.md

I'll add a new paragraph explaining all this on next version's cover letter.

Regards,
Nicolas

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