Weird boot issue

HelenF

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Now my CC Pandora has developed a problem.

The internal OS still boots normally, and SD cards still work fine from within that OS.

If I start the Pandora while holding the right shoulder, or if I start it with any card having autoboot.txt in the left slot, it hangs with a blank screen, with just the backlight and the rightmost LED on. It can still be rebooted with Pandora Button + Power Switch.

If I start the Pandora while holding Start, it boots the internal OS even if there is a card having autoboot.txt in the left slot. Is this a normal shortcut to bypass the autoboot?

I was playing around with the new recovery card, which did boot the first few times. I think I only tried the LED test. https://pyra-handheld.com/boards/threads/pandora-recovery-sd-card-image.98892/

Any ideas what could be wrong here?
 

levi

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How recent of an OS are you on on the NAND flash? And did you update it using an sd card reflash in the past few years? It might be that new big SD cards just take too long to be brought up from cold, and you need an updated uboot/something early to wait for them properly. Although if that were the case a soft reboot is likely to be able to see them properly the second time round, so it may not be that.
 

HelenF

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I'm not sure if I did an SD card reflash on this one. But it worked until just recently and then it stopped working, with the same SD cards. And I get the same problem from holding the right shoulder even if there are no cards in the slots - can someone confirm what a fully working Pandora does in that case?
 

FBnil

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If you bump the Pandora while on, it could corrupt the Nand and it will not boot up (I think I had that around 3 times during my daily usage of the Pandora)
 

levi

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Yes, but unless you were doing an sd card update while it was doing that, it shouldn't have been writing to the uboot partition. Reporedly, once the unit has booted from the NAND flash kernel and filesystem, everything appears to be okay, so to me it only sounds like uboot or something earlier in the boot process is playing up.

As far as I can recall, if you cold boot a pandora with the R-button held it should show a menu on the lcd screen. My LCD has been disconnected for a hell of a long time now and since my tv-out cable exploded I can't tell what the unit is doing, but that's my recollection.
 

HelenF

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I imagine it should be possible to reflash the bootloader from within the OS (and backup what's there now for later inspection). Though if that goes wrong, it won't boot at all.

I'm reading the boot article again: https://blogs.distant-earth.com/?p=79
Sounds like holding the right shoulder should give a menu, even if there no cards in the slots.
There are USB and serial boot modes too.
It does say the peripheral boot order key is Start, while ED just said it's Pandora+Start.
 

levi

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That blog post was written two years before I got my GHz pandora, so I consider it to be really early stuff, possibly written about a devboard or early CC unit. It's still right as I recall that R booting should result in a menu on screen, but the key to enter peripheral boot mode does seem to have changed since then - I don't know if that's because of an updated boot rom included in the later units, or some way in which it's been configured.
 

HelenF

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It's the hardware boot ROM, so any change would have to come from what's physically wired up to a particular input pin on the SoC.
 

levi

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Yes, unless the hardware boot rom has access to a small area of flash actually inside the CPU which contains the MLO/X-Loader and the full u-boot for a full NAND boot at least.

Your bootable SD cards presumably only contain an autoboot.txt and a kernel, on top of the LFS. I've never seen a bootable SD card with an MLO on it but that blog post suggests it's possible.
 

HelenF

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The hardware boot ROM normally loads MLO/X-Loader from the NAND, which then loads u-boot from the NAND. U-boot can then boot the main OS from the NAND, or SD cards having "boot.txt" or "autoboot.txt".

ED's new rescue card image includes files "MLO" and "u-boot.bin", as well as "autoboot.txt". When the Pandora is powered on with the magic keys held, the hardware boot ROM is supposed to load the MLO file from the SD card, which is then supposed to load u-boot from the SD card. Unfortunately, there seems to be no way to verify which of these steps is failing. (And on a working Pandora, you can't see whether the special boot worked or not, because it might just have gone NAND X-Loader -> NAND u-boot -> autoboot.txt.)

I had an idea that the X-Loader and u-boot for the SD card could be built to do something visibly different, e.g. light a certain pattern of LEDs each and wait a second. Don't know how practical that is.

----

Anyway, questions for someone with a working Pandora:
  • Please can you confirm what you see if you power on the Pandora while holding the right shoulder with no cards in the slots?
  • If you have an autoboot.txt bootable SD card in the left slot, and power on the Pandora while holding the Start button, does this bypass the autoboot and load the OS from the NAND?
 

HelenF

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Thanks! I wonder what exactly Start is doing on mine then. I'd appreciate if someone with a CC Pandora could check those things too, just in case it's different. (Though come to think of it, both of those things are probably software, so could have been updated at some point.) Never mind, I got something different to happen...

I think my CC is sorted?


And apologies, ED didn't exactly say the magic key is Pandora+Start. It sounds like maybe the Pandora key is supposed to make it turn off, then Start activates the SD boot right afterwards. I'm not sure about that.
 
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