comments in Makefile wrongly state that avrdude needs zeros to be written for unused fuse bits

[bkerin]

The comment was right before avrdude 6.3 but 6.3 and later correctly require you to write ones, and I believe I've had the verify fail if I don't. Not sure if optiboot is on an older avrdude or if the verify isn't normally done or what.

[WestfW]

Optiboot pre-dates Avrdude6.3, so the comments refer to older versions. avrdude is NOT "included" in optiboot, so it isn't "on" a particular version. I'm not sure what to do with this sort of backward-incompatible change in "external" tools.

From the Avrdude config files recently, it looks like the fuses are supposed to support "don't care" bit values. Does that just "not work" yet?

[bkerin]

On Thu, Apr 20, 2017 at 8:46 PM, Bill Westfield ***@***.***> wrote: Optiboot pre-dates Avrdude6.3, so the comments refer to older versions. avrdude is NOT "included" in optiboot, so it isn't "on" a particular version. I'm not sure what to do with this sort of backward-incompatible change in "external" tools. From the Avrdude config files recently, it looks like the fuses are supposed to support "don't care" bit values. Does that just "not work" yet?

I think it works like it should now: IIRC atmel datasheets say you're supposed to write unused fuses to 1 (unprogrammed). I think current avrdude fails on a verify or something you don't do this. Unfortunately I think that is the opposite of what older avrdude needed, though I'm already starting to forget exactly why. I know I had to change my build system when I went to 6.3 and the changes seemed good. But I didn't try to maintain compatibility with old avrdude versions. Britton

[per1234]

Just adding some additional information on this:
Arduino has modified their version of AVRDUDE 6.3 to be backwards compatible with the old fuse values:
arduino/avrdude-build-script@8f26fd1
arduino/avrdude-build-script@edfbcc9
arduino/avrdude-build-script#2
A patch for this was submitted upstream:
https://savannah.nongnu.org/patch/index.php?9110

[WestfW]

I changed a couple of the fuse settings in a50f47b
Pretty much just for my convenience during testing with a "stock" avrdude.
But I still think it's an avrdude problem :-)

[WestfW]

Need to go through and fix more of the legacy targets, and boards-1.6.txt