valueforvalue
Well-Known Member
Alright everyone here is a little bit more information for ya on /dev.
I now know why everything gets cleared upon reboot and you start with a fresh /dev. It's actually very simple the /dev "partition" is actually not a partition at all. It's a tmpfs which means temporary filesystem. Basically it is a ramdisk, or ramfs they behave almost identically to one another. There is a good article on the difference i will post a link to.
It's easy to verify what I am saying just pop into your favorite terminal emulator and type "mount" without the quotes and you will see a list of the mount points on your phone. tmpfs is mounted to /dev and is near the top of the list. Why is it created as a ramdisk? Basically it makes things less complicated for the kernel when it boots because it can write all of the /blocks and /ttys etc before anything else is loaded. It then mounts tmpfs to /dev for convenience. In short /dev is actually stored in volatile ram which means anything on it will not survive a reboot.
So the dalvik cache move script actually moves the cache to ram. One thing I am uncertain of at this point is if it being in ram effects the available ram you have for applications. At this point I don't think it does. I've done a few tests and it seems that these phones might actually have 1gb of ram but a little over half of it is reserved for system use. Which includes the 200mb /dev has and also there are two other tmpfs mount points that have 200mb a piece with none or that space used whatsoever. According to my task manager I have 400mb available for application use. Add the 600mb occupied by the tmpfs then you end up with about 1GB.
In short this simply means there is no way to make changes to dev stick between reboots. So /data/data won't be able to be moved there period. No modification could make it possible that it know of. Hope this information helps clarify this for anyone who was curious.
Here is the link to the article explaining the differences between tmpfs and ramfs http://www.thegeekstuff.com/2008/11/overview-of-ramfs-and-tmpfs-on-linux/
I now know why everything gets cleared upon reboot and you start with a fresh /dev. It's actually very simple the /dev "partition" is actually not a partition at all. It's a tmpfs which means temporary filesystem. Basically it is a ramdisk, or ramfs they behave almost identically to one another. There is a good article on the difference i will post a link to.
It's easy to verify what I am saying just pop into your favorite terminal emulator and type "mount" without the quotes and you will see a list of the mount points on your phone. tmpfs is mounted to /dev and is near the top of the list. Why is it created as a ramdisk? Basically it makes things less complicated for the kernel when it boots because it can write all of the /blocks and /ttys etc before anything else is loaded. It then mounts tmpfs to /dev for convenience. In short /dev is actually stored in volatile ram which means anything on it will not survive a reboot.
So the dalvik cache move script actually moves the cache to ram. One thing I am uncertain of at this point is if it being in ram effects the available ram you have for applications. At this point I don't think it does. I've done a few tests and it seems that these phones might actually have 1gb of ram but a little over half of it is reserved for system use. Which includes the 200mb /dev has and also there are two other tmpfs mount points that have 200mb a piece with none or that space used whatsoever. According to my task manager I have 400mb available for application use. Add the 600mb occupied by the tmpfs then you end up with about 1GB.
In short this simply means there is no way to make changes to dev stick between reboots. So /data/data won't be able to be moved there period. No modification could make it possible that it know of. Hope this information helps clarify this for anyone who was curious.
Here is the link to the article explaining the differences between tmpfs and ramfs http://www.thegeekstuff.com/2008/11/overview-of-ramfs-and-tmpfs-on-linux/