The word is some Android users have been experiencing problems booting their device after flashing a custom Android Jelly Bean ROM, leading to kernel problems because most custom Jelly Bean ROMs need two framework.jar files to contain all the features of the ROM.
According to an article over on Rootzwiki many custom kernels are apparently only loading one framework.jar file at boot, which means the smartphone is prevented from booting properly.
Apparently the framework.jar file can only archive a limited quantity of methods before it will no longer compile, and due to recent changes in Android Jelly Bean, the framework.jar is close to its limit just using stock methods.
According to the article, until such times as Google comes up with a solution, custom Jelly Bean ROMs will need to adopt a workaround posted by Cyanogen, which is to split the methods used by the ROM into 2 files, framework.jar and framework2.jar.
ROMs that are stock with a few tweaks shouldn’t have this issue, as they can still run with just one framework.jar, and users can flash any kernel they wish and it should load correctly depending on kernel quality and the if user followed the instructions correctly.
Whilst for CM10 and others that have added customisations and features the 2 framework archives have to be loaded by the kernel at boot.
Teambamf member Adrynalyne has pointed out that kernel devs will either need to code their init.rc configurations to incorporate framework2.jar in BOOTCLASSPATH, or use the Anykernel template when they develop kernels.