Limit to number of flashes?

Hi empeg tech guys,

Is there a limit to the number of times you can flash something to the flash ROM, such as a custom kernel, a boot logo or an official update? It used to be that flash ROM's would crap out after so many times, I was wondering if this is true for the empeg.

/Pepijn

Wow, good question. I was never aware there was such a limit to flash. Hugo?

___________
Tony Fabris

Woohoo I know something Tony doesn't know! This is my lucky day!

The minimum flash cycles is 100,000 which Hugo originally mentioned in this thread.


-Tony
MkII #554

Interesting. If one reads that thread, it's interesting to note that the logo updates are the least of our worries.

The real bugaboo would be the other stuff that's written to flash: The player state on bootup/powerdown.

I wonder: Is the flash write limitation on an address-by-address basis, or is it global to the entire flash chip? In other words, if it starts forgetting its player state because it's been powered down 100,000 times, does that mean you can no longer upgrade the logo, either?

I did a little calculating, and if you powered the unit down and up four times a day every day, it would take 68 years to reach 100,000 flash writes.

Damn, my empeg has a Year 2069 bug.



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Tony Fabris

My understanding of flash is that it's an address-by-address basis... Like, the same location can't be written to more than X times... Other locations on the flash chip should still be fine.

I can't imagine circumstances where anyone would be writing to ANY location on the flash 100,000 times throughout the life of their Empeg.

-Tony
MkII #554

I can't imagine circumstances where anyone would be writing to ANY location on the flash 100,000 times throughout the life of their Empeg.

Well, we'll just have to see how we're all doing in 2069.

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Tony Fabris

Hmm, if my Empeg lives that long I'll be happy... If *I* live that long, I'll be ecstatic! And senile...

-Tony
MkII #554

My understanding of flash is that it's an address-by-address basis... Like, the same location can't be written to more than X times... Other locations on the flash chip should still be fine.

Thats how I remember it as well, and this is why I believe the current state data is moved around quite a bit. I'm sure the exact number of spaces could be found in the kernel source. This in effect would then turn the real limit into 100,000 custom logo changes/upgrades before an issue arrises.

Actually, it's 100,000 erases, not programs.

We store 128 bytes of state information on power down, and I worked out a neat algorithm (I'm sure someone else must have done this before, but...). We cycle through a single 8k page - at power up we work backwards through the page until we get a 128-byte block with a correct CRC, and note that on the next powerdown we have to use the next free slot in the page.

This means we get 8192/128=64 power downs for each 8k page erase, and more like 6.4 million powerdowns (minimum).

The limitation is *per block*. The blocks below 0x10000 (64k) are 8k, above that they are 64k.

Hugo

What a clever little boy you are.

___________
Tony Fabris

Of course by then you'll have twin 200 terabyte holographic drives so you can watch 3-D movies (a different one for each passenger) while your flying car takes you to to work (where there's still a better 'net connection). Although you worry the new teleportation device will finally render your empeg mkII obsolete....
:-)
-Zeke

just say you weren't paying much attention...

Not necessarily... I heard that SonicBlue is preparing to announce the "Teleportation Module" very soon. They anticipate shipping them early next week, but there may be some "slight delays" as order fulfillment problems are ironed out...

-Tony
MkII #554