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Re: single device to replace ADSL router, WiFi/Ethernet router, SIP router?



On Thu, Dec 22, 2011 at 12:01:17PM -0800, Bill Gatliff wrote:
> I really, really hate this idea.  :)  I much prefer having a
> bootloader in NAND, so that I'm not beholden to all the i/o necessary
> to read it from somewhere more complicated and less controllable.

It supports loading it from SATA, NAND, NOR, uSD, and a few other places.

> In addition, I really, really hate the quality levels I am seeing with
> uSD/eMMC devices right now.  I know they are all internally based on
> NAND, why not ditch the little microcontroller they must also include
> and talk to a NAND directly?  One less part to break, and one less
> thing to question the sanity of when you switch that device from FAT
> (which it is almost certainly optimized for) and extN or equivalent.
> (OT, but I wonder if the hangs and hiccups I see often enough to worry
> about aren't in some way due to the microcontroller's assumptions
> about the filesystem in use).

The uSD is just what the quick start board is configured to use.  The CPU
supports a number of choices.

> Finally, obviously what you are calling the "bootloader" in your board
> is merely a second-stage one, as the CPU almost certainly does not
> natively know how to read from uSD.  A first-stage bootloader must
> exist somewhere in the SoC itself.  That doesn't really matter if you
> are happy always reading from a presumed-functional uSD, but as a
> platform integrator I would want to research what other options it
> makes available--- especially ones that would allow me to have a
> "factory reset button" on the unit that truly wipes the uSD and
> initiates a fresh download of a kernel and rootfs over https from
> somewhere.

The CPU does in fact seem to know how to do that.  The uboot it loads
is in fact the firmware that initializes it.  Putting a small bit of
logic/rom on the die that you can't destroy to make it simpler to boot
seems rather sensible to me.

And since one of the options is to use a NAND or NOR flash, for people
that want uboot always present even if other media isn't, that option
exists too, but now you do intriduce the possibility of bricking it if
you go to update uboot.

> Don't get me wrong, I like the Quick Start board too (I think I have
> one on my desk somewhere, actually).  But I don't like the temptation
> to turn something like that into a product without a lot of additional
> thought.  I'm looking at you too, Beagleboard.  :)

-- 
Len Sorensen


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