linux-kernel - Re: [PATCH v2] ARM: dts: BCM5301X: Linksys EA9500 add fixed partitions

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Date:   Mon, 9 Nov 2020 12:58:31 -0500
From:   Vivek Unune <npcomplete13@...il.com>
To:     Rafał Miłecki <zajec5@...il.com>
Cc:     florian.fainelli@...adcom.com, Hauke Mehrtens <hauke@...ke-m.de>,
        bcm-kernel-feedback-list@...adcom.com,
        Rob Herring <robh+dt@...nel.org>,
        linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] ARM: dts: BCM5301X: Linksys EA9500 add fixed
 partitions

On Mon, Nov 09, 2020 at 06:28:38PM +0100, Rafał Miłecki wrote:
> On 01.11.2020 21:08, Vivek Unune wrote:
> > This router has dual paritions to store trx firmware image and
> > dual partitions for nvram. The second one in each of these cases acts
> > as a backup store.
> 
> I'm quite sure CFE is supposed to flash new firmware to the backup
> partition and then mark it as main one. The old firmware partition becomes a
> new backup then.
>
> That means you need to check which partition bootloader used to handle
> partitioning properly.
> 
> 
> > +		partition@...000 {
> > +			label = "firmware";
> > +			reg = <0x0200000 0x01D00000>;
> > +			compatible = "brcm,trx";
> > +		};
> > +
> > +		partition@...0000 {
> > +			label = "failsafe";
> > +			reg = <0x01F00000 0x01D00000>;
> > +			read-only;
> > +		};
> 
> Here you assume CFE always boots from the first firmware partition.
> 
> Unless EA9500 CFE does sth stupid it seems like a 50% - 50% guess.

Hi Rafał,

Indeed, my assumption is to only boot using first partition.

If we ever want to support true dual partitions in future, we need to:

1. Read the boot flag 'bootpartition' and skip the backup partition parsing
2. Updagrading firmware will write to backup partition and flip the bootpartition


Thanks,

Vivek