[U-Boot] uboot redundancy.

[Joakim Tjernlund]

Sagar Heroorkar <sagar.heroorkar at gmail.com> wrote on 2010/07/21 17:21:31:
>
> Hi All,
>
> Before i start using your ( Joakim )approach. I would like to get some tips
> from Wolfgang or someone who can assist me here.
>
> I am working on nor flash which is 128 mb flash for the PPC4XX.
>
> My  goal is to make uboot redundant. having other copy of uboot if one fails to boot.
> Architechure follows like this.
>
> Totally there will be 3 uboots. Golden uboot is the one which has basic logic
> to pick which uboot from uboot 1 or uboot 2 (different copy).
> uboot 1 and uboot 2 is flashed into some location of 16mb nor flash.

Seems sane.

>
> Steps follows like this.
>
> 1)G-boot picks up uboot1/uboot2 based on environment variable. Basically we
> jumps to that uboot and start booting it from there.

Doesn't need to be an env var. I image one could mark each image (uboot 1 or
uboot 2) with a flag instead. That way you don't need to parse the env.

>
> When i analysed the approach what Joakim implemented in http://www.mail-
> archive.com/u-boot at lists.denx.de/msg26918.html.
> He uses something like link_off() for each of the global data.
>
> * There will be too many link_offs() i have to use in uboot to make sure each
> of the global data.

There are a few link_offs() but not too many IMHO. Remember that my patches
were complete for my board.

> * As i will have 2 uboots which resides into seperate partitions. This requies
> to build 2 uboots with different relotate_code logic/something .

Yes, this is the other way, you need to build two images linked to different
addresses and select the right one at install.

>
> I have read comments about this approach in the link what i pasted above.
>
> I would really appriciate if anyone replies (especially Wolfgang ) about
> whether to go head with this approach before i spent much time on this.
> Also if anyone has already done similar implentation for any of the boards let me know.
>
> -Sagar
> On Mon, Jul 19, 2010 at 4:36 PM, Joakim Tjernlund <joakim.tjernlund at transmode.se> wrote:
>
>
> Sagar Heroorkar <sagar.heroorkar at gmail.com> wrote on 2010/07/19 15:26:20:
> >
> > Hi Wlfgang,
> >
> > resending this.
> >
> > Please do reply
> >
> > -Sagar
>
> > On Fri, Jul 16, 2010 at 3:12 PM, Sagar Heroorkar <sagar.heroorkar at gmail.com> wrote:
> > Hi Joakim,
> >
> > Graeme referred me to contact you for this.
> >
> > I am working on U-boot making it PIC for ppc 405ex based boards.
> > I see in the following link http://www.mail-archive.com/u-boot@lists.denx.de/
> > msg26918.html
> > that you have implemented similar thing on 83xx board.
> >
> > I have downloaded latest u-boot from ftp server of denx. I dont see the
> > functions what you have modified like LINKF_OFF() etc.
> > I would like to know where is the source code for that. Also is there any
> > document other than the mail thread that explains what you have chagned.

> Hi Sagar
>
> The source isn't in u-boot. It is only available as the patches I sent at the time.
> I don't have the patches handy as I am on vacation for 2 more weeks.
>
> >
> > Thanks in advance.
> >
> > -Sagar
> >