Author: Wookey Date: To: balloon Subject: Re: [Balloon] Accessing NOR flash from Linux
+++ Nick Bane [2011-06-09 10:44 +0100]: > On 08/06/11 14:56, Patrick Doyle wrote: > The history of this goes back to Balloon2. There were two NOR flavors.
> The standard version was a moderately large CFI compliant chip. The
> largest Balloon2 customer (TCL) used a tiny non-CFI NOR (and a CPLD
> instead of FPGA) that had a fake CFI shim welded into bootldr to support
> it. This made exposing the NOR in the linux kernel a nuisance and also
> was a brick-your-balloon option for users. It was decided on balance to
> not expose the NOR as a flock of mtd partitions and keep it in the
> bootldr domain.
> Balloon3 is of course much simpler but the "dont-expose-your-NOR"
> principle was sort of carried over.
> My preferred solution would be to upload replacement FPGA images from a
> booted Balloon3 using a firmware loader. This means you could have
> multiple FPGA images to test/compare.
I agree that making the FPGA upload use the firmware loader
infrastructure is a good idea, (upload direct to device or to NOR boot
store needs a bit of thought) but that's no reason not to also fix the
problem of difficult NOR access fro userspace.
The history of the previous edition of the board from
2003 really shouldn't be a good reason for making the NOR hard to
access from userspace.
Now that 1.0 is out the door, we can make changes to the system if
necessary (although we can probably order the devices so as not to
break the boot with a bit of care)