[Galaxy Note GT-N7000 Android Development] rdhoore108:
Thanks very much osd_daedalus for your thoughtful replies!

I was running the original Gingerbread till last week, thinking that if it ain't broke, don't fix it... My Note1 would occasionally suddenly restart, but that behavior stopped when I tightened the screws in the back (to fix the bad GPS signal, a cure which actually works). But it would never, ever freeze. However, my banking app did not support Gingerbread. Samsung's update to 4.1 (or whatever it was) failed without explanation, so last week I decided to update to a Kitkat 4.4.4 custom ROM. I tried many ROM's, but the phone would freeze many, many times a day.

The freezing I had in Kitkat was : the screen would stop updating (except for the rotating charging battery icon which would continue to rotate), it would not respond to any buttons (including power), nor touch screen, but my bluetooth music would continue playing for a few minutes. Then suddenly the music would stop, and the battery charging animation would stop. Then I had to hold the power button pressed until it would restart. Sometimes I had to do that 6 times in a row until it would work properly without freezing (for a while). It would also freeze at night, while simply charging (and failing to wake me up for work in the morning). Needless to say, I got extremely sick of it, and scanned the web far and wide for possible causes and solutions. I discovered the EMMC bug (wiki . cyanogenmod . org/w/EMMC_Bugs) [I'm not allowed to post outside url's yet], and thought I had found the cause of all my freezes, because tests indeed revealed that my flash had a bad section, and the symptoms of the bug are exactly that Android pretty much freezes (if the problem is not in the boot partition, then it's bricked). But then it turned out my partitions already avoided the corrupted area. So, that was not the reason.

So, then I concluded the problem is inherent in KitKat for GT-N7000, and I should maybe try this Lollipop ROM. Here I didn't have freezes, but twice the coming to a crawl, to the point that it's as good as frozen. But in the two days that I'm running it now, I only had this twice, so it's a kind of "improvement" compared to the many, many freezes in KitKat :)

The cpu going crazy and superheating the phone and draining the battery is more of a problem. It hasn't happened today yet, but the only thing I've done is make some calls, read some mails (gmail) and read a bit of news with the Google News app at lunch break. The battery is still on 78%, which is very good for 8 hours of use. After I gather some courage, I might again try Facebook Messenger, and gradually some more apps, one by one with a few hours in between, and hope to find what triggers the problem.

I was not aware that this ROM is using ART by default... Nice.

At this point, I am willing to do a lot to find out the cause for the CPU going crazy.

That's interesting indeed... I will try without external SD, you have a point there.

Bauner is suggesting to use vfat for internal SD, I will try that. I had formatted it as exfat. Using vfat might not fix my problems, but then it also might, who knows, and it sounds like it won't harm.

I can imagine it must be very, very difficult for a developer to figure out the cause. Every user is doing different things, like re-installing different apps and data from Titanium, using different Android settings, having differently partitioned phones, different external SD cards (or none) etc.

---------- Post added at 01:42 PM ---------- Previous post was at 01:17 PM ----------

Thanks very much, bauner, for explaining this. I formatted internal SD as vfat now (it was exfat indeed), and also cleared the Dalvik/ART cache just for fun, while I was there. Now Android is rebuilding it. I will definitely keep you updated, I won't do the factory reset at this point but will try the gradual process of using different apps one by one.

While I'm at it, here is my partition table, I hope it looks fine. The area from 1073 to 2148MB is corrupted by Samsung's EMMC bug, so the area around it is not used.

Model: MMC VYL00M (sd/mmc)
Disk /dev/block/mmcblk0: 15.8GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt

Number Start End Size File system Name Flags
1 4194kB 25.2MB 21.0MB ext4 EFS
2 25.2MB 26.5MB 1311kB SBL1
3 27.3MB 28.6MB 1311kB SBL2
4 29.4MB 37.7MB 8389kB PARAM
5 37.7MB 46.1MB 8389kB KERNEL
6 46.1MB 54.5MB 8389kB RECOVERY
7 54.5MB 264MB 210MB ext4 CACHE
8 264MB 281MB 16.8MB MODEM
9 2149MB 3042MB 893MB ext4 FACTORYFS
10 3042MB 6042MB 3000MB ext4 DATAFS
11 6042MB 15.8GB 9716MB fat32 UMS msftres