CODEWITHSUNDEEP
androidoptimizationvirtual-machineloaderdalvik
xmllmx
xmllmx

Reputation: 42379

Why do we need to put the *.odex files under /system/app even if we already have /data/dalvik-cache?

For instance, we have phone.apk and phone.odex under /system/app. According to some unofficial documentation, phone.odex is used to expedite the process of loading an app. However, why do we not just put phone.odex under /data/dalvik?

What's more weird is: There exists a file named system@app@[email protected] under /data/dalvik, when the app is loading, which one takes priority to load, /system/app/phone.odex or /data/dalvik/system@app@[email protected]?

Is it totally redundant to put phone.odex under /system/app?

Upvotes: 3

Views: 7319

Answers (1)

fadden
fadden

Reputation: 52343

The /system/app directory is read-only on normal (non-developer) devices, and only updated when the system receives an update. The point of /system/app/*.odex is that the .odex file can be delivered as part of a system update, so it doesn't have to be generated on the first post-update boot, and doesn't eat up space on the /data partition.

If the .apk and .odex files are out of sync, the system is not able to overwrite the .odex in /system/app, and will try to generate a correct version in /data/dalvik-cache. Normally this will fail, because when .apk and .odex are delivered in pairs, the .apk does not contain a .dex file (it would be redundant to do so).

The .odex in /system/app is scanned first, so it essentially takes priority.

Finding a redundant .odex is not expected, and suggests that at some point the device had a phone.apk that included a .dex and that did not match the .odex.

Upvotes: 6

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