It from what appears to be an account created recently, apparently specifically for the purpose below:And the point of this thread is?
contradict @tsialex.
The amount of free space left in your screenshot above is dangerously low.
My vote is with experience.
I'm curious about the way you're analyzing these dumps.My experience is now based on analyzing hundreds of dumps from dozens of 5,1 and 4,1->5,1 machines.
I'm curious about the way you're analyzing these dumps
The amount of free space changing on the SPI flash after each reboot is normal behavior, as far as I understand. This can be affected by the garbage collection routine. The problem arises when certain operations require many variables to be stored in the flash ROM (such as during an OS update), and there's not enough available space remaining. With your first screenshot showing less than 4k bytes, what happens if that does not free up after a reboot during an OS update? I assume it could lead to corruption elsewhere in the ROM.The amount of free space is actually changing at every reboot, this is the little "secret" nobody will tell.
With your first screenshot showing less than 4k bytes, what happens if that does not free up after a reboot during an OS update?
The problem arises when certain operations require many variables to be stored in the flash ROM (such as during an OS update), and there's not enough available space remaining.
Interesting. Well, I myself don't know too much about the inner workings of the SPI flash ROM, but I am concerned about it from a longevity perspective. I'm interested to read more about the behavior you posited above, as this is the first time I've heard about there being a specific, repeatable pattern to ROM memory management.After every reboot, the free space decreases with something between 7000 and 8000 Bytes. And when the remaining free space of the 1st VSS store is less than that (at the 8th reboot for this particular machine) it does free up. This is how the NVRAM really works, this is the point.
I am concerned about it from a longevity perspective.
So what happens if you are running an update that needs to store large data and you are on the 6th or 7th reboot of the garbage collection cycle for instance? Are you saying the firmware will realise it needs more space in advance and trigger the garbage collection even though it would only have ordinarily done this on the 8th reboot?This is what I used to believe a few months ago.
There hasn't been a lot of focus on this but this is how the NVRAM works.this is the first time I've heard about there being a specific, repeatable pattern to ROM memory management.
So what happens if you are running an update that needs to store large data and you are on the 6th or 7th reboot of the garbage collection cycle for instance? Are you saying the firmware will realise it needs more space in advance and trigger the garbage collection even though it would only have ordinarily done this on the 8th reboot?
We wait with bated breath!I will tell everybody exactly what happened.
Thanks. I just figured the garbage collector would run after each reboot, or if a set threshold was reached. I didn't realize it would take up to 8 reboot cycles for the memory to be dumped.There hasn't been a lot of focus on this but this is how the NVRAM works.
There is one example where it is set out:
Mac OS 11.3 has broken support for older Mac Pros
I ran the tests again, this time I took care to set Startup Disk from the prefpane to the Big Sur 11.3 Disk. I restarted more than 20 times, this time logging the nvram free space thru a complete nvram circle (from filled to full to garbage collection to the same filled situation) and it...forums.macrumors.com
Seems to vary. Was the 10th reboot in the linked example.I didn't realize it would take up to 8 reboot cycles for the memory to be dumped.
Can I ask the purpose of analysing hundreds of dumps - are you looking to solve the issue of bricking or ??My experience is now based on analyzing hundreds of dumps from dozens of 5,1 and 4,1->5,1 machines.
are you looking to solve the issue of bricking
OK - so i don't mean to be rude, but what are you doing?You can say that too, but mostly I'd like to know what I'm doing, whatever I'm doing.
. /Volumes/Macschrauber\'s\ CMP\ Rom\ Dump/RomDump\ Macschrauber.app/Contents/Resources/test_nvram ~/ck.bin
serial from firmware: CK2xxxx
MP51.88Z.0089.B00.1806081708
25 Memory Configs (ok)
2 xml (ok)
0 iCloud Tokkens (ok)
0 Microsoft Certificates (ok)
2 BluetoothActiveControllerInfos (ok)
2 BluetoothInternalControllerInfos (ok)
2 current-network (ok)
9 AAPL Path Properties (ok)
Length of 2nd VSS Store is wrong (FF FF FF FF)
7616 Bytes free space of 65472
I don't see the notification about VSS2 being empty after triggered garbage collection.