Design proposal for dual BMC flash with "golden image"

[Ivan Mikhaylov]

On Tue, 2020-09-15 at 11:38 +0800, Lei Yu wrote:
> > - A series of patches for implementing flash locks for Macronix chips that
> > we
> > use
> > - A utility which gives control of golden side, called `gftool` and
> > providing
> >   abilities to:
> >   - lock/unlock golden side
> >   - reboot into golden side
> >   - reflash golden side from main
> > 
> 
> Does the lock/unlock function work on the Macronix chip only? Does it
> apply to other chips?

It can be applied to different chips, macronix locks are not supported for now
in upstream. You can check here - 
https://elixir.bootlin.com/linux/v5.9-rc5/source/drivers/mtd/spi-nor , chipswith SPI_NOR_HAS_LOCK.  

> > Yes, but the watchdog series of patches is more like a hack for now.
> > We're expanding the watchdog api so that it grants the user control of WDT2
> > via
> > ioctl(watchdog start on reboot) and allows for rebooting into golden chip
> > using
> > WDT2. However the upstream kernel maintainers won't accept it as they say
> > it's a
> > driver level decision, and we're exporting it to the user. That's something
> > they
> > don't want to accept. That may be fine though as theoretically the patch set
> > may
> > be kept only in the openbmc linux kernel, but that will put an additional
> > support burden on Joel and the community. I'm discussing that with Joel.
> 
> OK, thanks.
> For now, we use "devmem" to manipulate the registers for testing purpose.
> It's nice to have that driver, but in productions there will be no
> need to use devmem nor the ioctl on watchdog, so it's not a must for
> us to use the driver.
> 

And how you switch safely into golden side in this case?

Thanks.