Kernel With Separate Cache Partition

Hello everyone,

I've compiled a kernel which separates the NAND memory into 3 partitions (well more then that but anyway). These partitions are system, data and cache like a native Android phone (which also has recovery but we don't need that). Previously cache was linked to a directory on the data partition which was constantly becoming corrupt causing errors on start-up. Often clearing dalvik-cache would allow Android to boot but data was lost. There's nothing to say that this will solve the problem but i'm giving it a go so thought I would post it up for you to try also.

The cache partition is 20mb which means the data partition is only 90mb or so. If you like a million apps on your phone either put some on your SD card or don't use it

I haven't completely incorporated this partition into the initrd which means that currently it will only mount if data is also on NAND but this can be changed easily enough, but for testing purposes I want everything on the NAND chip anyway.

Downloads from market on all versions of Android, unless the init.rc directory is changed in Gingerbread, all go to the cache partition and are deleted on restart. What this means is that you can't download and install an app larger then 20mb (which isn't recommended anyway with the small amount of data space available). This is a drawback but for those that use data on SD it should be possible in the future to utilise more of the NAND memory for cache so you can install whatever you want. I don't know of many apps larger then 20mb anyway though.

I have included a modified version of ATools in the zip. The standard version will overwrite the partition values and the kernel won't work properly so if you need to modify the kernel use the version included. It is also important that you DO NOT change the system or data partition sizes in ATools as this hasn't been modified to account for the cache partition so will mess it all up.

I have also included an androidupdate.tar modules update for the kernel in case your wifi doesn't work after flashing the kernel.

I think that's it for now, let me know how it goes!

EDIT::
One last thing, you will need to wipe your DATA partition to use this kernel because some of your data may be positioned where the cache partition is now, so if you load this kernel and android is heavily corrupt you know what you have to do!

To check the kernel is working correctly you can type "df -h" into a terminal and it should show all of the current partitions including one called cache on mtdblock4.

Should now work with polaris, kaiser and vogue. There is a VOGUEIMG.NBH included for those who have trouble with ATools. It is completely untested on Vogue so sorry if it doesn't work.

EDIT

I have re-uploaded a modified kernel because there was some issues with data with the last one. If you have already applied the last one flash the new one and apply the module update again

First couple of days of heavy use I've had in ages with no corruption. First day of my new job today so it's been on Google Navigation for 3 hours and used extensively during the day. Had to do a hard reset at one point and everything was fine. had a few soft reset's too. Don't get me wrong, i'd be surprised if this is a fix, but it's been a while since I've used my Kaiser this much and not had to wipe my data partition!

daedric said:

scooter1556 , i have a question. It is not the purpose of the thread or kernel, but how difficult would it be to activate scalling of the cpu ?

Right now, the two 3 biggest issues with Android on the Kaiser are, IMHO, Data corruption, Battery life, performance.

Please share your thoughts

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Well in theory not too hard, there is a feature built into the linux kernel called cpufreq which is currently disabled in our kernel because our cpu and chipset code doesn't support it but krazy-killa has been working on getting it working in his kernels with a little success as far as i'm aware but i'm not that sure. I haven't personally looked into it but if I get some spare time I definitely will. I've started a new job now which i'm sure will keep me quite busy but I still intend to so some work on the Kaiser when I get time

PoXFreak said:

Made 2 mistakes when building kernel (selected tilt instead of normal and forgot to OC to 480MHz), and running kingshui's 12/15/2010 build 2.2.1. seems ROCK solid and fast! I applaud your use of ramzswap for the extra 20mb, bravo!
I'm just hoping I can go back and rebuild the kernel with the correct settings without messing up the system/data/cache partitioning.

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They aren't mistakes, those are the settings I need for my Kaiser. I included a modified version of ATools for you all to modify the kernel for your devices as I stated in the first post

a.s.j said:

1) What filesystem is used for the cache? If YAFFS, could it get corrupted? If Yes, what would happend then?
2) Is it really needed to have 20MB for the cache? ATM it seems to be used only by a like 1-2MB on the cache partition, would not it be enough to have for example 10MB for the cache leaving more space for apps?
3) What is the difference using apps in the system and data partitions? If I would run off the space on the data partition, can I put some apps in the system apps folder to save the space without wandering about how it works?

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1) The cache partition is still using Yaffs2 because it is the easiest filesystem to configure at the minute, but the idea of making it a separate partition like on a native android device is that it can be changed to another filesystem in the initrd relatively easily. If it gets corrupted it will do what it used to I guess, but I haven't had any corruption as of yet so it's difficult to say. Hopefully if the cache partition get's corrupted it shouldn't affect data so you should just be able to wipe and format dalvik-cache in the install menu.

2) I made it 20mb because most android devices have 30mb or bigger and this is mainly because market app downloaded get downloaded here before being installed, so if you installed google maps for instance it would use up 6mb, plus the standard 1-2mb normally being used, but if you only had a 10mb cache for instance, you would only be able to install apps less then 8mb which is a little limiting really. I don't really care much about installing lots of apps in data or on the phone at all for that matter so having 95mb for data is more then enough for me.

3) You can put apps in the system partition in /system/app. The system partition is read only so all data for the app still goes to the data partition. You can still save a little data partition space though if you need it. Most installs of android are 80-95mb which should leave you 5mb or so to play with. Some all language builds pretty much use up all of the partition though so you need to look and see what space you have to play with before putting apps on the system partition. If you overload it you will probably end up corrupting it and having to reinstall. But to answer your last question, the system partition works in the same way as the data partition apart fro the fact that it is read-only and data is read/write.

PoXFreak said:

Scoot:
I understand that the settings built into the .nbh are for your device. What I was meaning was I needed to modify the CPU clock up to 480MHz, and for some odd reason my device swaps the "@" and "!" buttons if I set it to "tilt", among other buttons being set wrong.
Also, I am used to having the left and right softkeys set as "vol up" and "vol down" respectively. Is this something I need to make an androidupdate for, or do I have to write a new NBH?

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Can you not do all of this using the ATools i provided in the attachment in the first post? You should be able to load the nbh into ATools and then set the CPU speed, change the keyboard type and remap the buttons and then save it before flashing. Just don't change the partition sizes as this will mess up the cache partition I added until I make it more permanent.