Database Develop

[Q] Why clear Dalvik and cache?

So every single rom for any phone I've seen says to clear the dalvik and the cache (or maybe its just the "dalvik cache") but when I went from stock to Thriller, I forgot to, and nothing went wrong. In fact, all my settings and apps were all intact from the previous stock rom.
I've considered that the only other phone I'd done any flashing on was a backflip, without Apps2SD and maybe that's why all my apps and settings were intact, so that still leaves me with the question: why clear it?
This may be a noob-ish question, and I apologize. Thanks for any help!

Tyqar said:
So every single rom for any phone I've seen says to clear the dalvik and the cache (or maybe its just the "dalvik cache") but when I went from stock to Thriller, I forgot to, and nothing went wrong. In fact, all my settings and apps were all intact from the previous stock rom.
I've considered that the only other phone I'd done any flashing on was a backflip, without Apps2SD and maybe that's why all my apps and settings were intact, so that still leaves me with the question: why clear it?
This may be a noob-ish question, and I apologize. Thanks for any help!
Click to expand...
Click to collapse
If there are any compatibility issues between the apk dalvik cache of your previous rom and the apks on the new rom wiping dalvik clears the previous apks stored dalvik cache. In most cases you can flash without a problem. But I recommend wiping between rom flashes just to eliminate any potential problems. Flashing something like Thriller over the stock rom you can probably get away with not wiping anything since all the apks are essentially the same. Flashing kernels you don't need to wipe anything. When flashing a rom with a completely different firmware I recommend a full data wipe. Restoring recovery backups such as nandroid require no wiping at all.
Also, wiping dalvik shouldn't affect any of your settings.
Sent from my LG-P920 using Tapatalk

+1
When switching ROM with different base apps, it is generally better to wipe caches than to get stuck in a boot loop, or having your apps and launcher FC on you. You never lose anything as the cache rebuilds itself on the next reboot, except maybe a few minutes
CallMeAria said:
If there are any compatibility issues between the apk dalvik cache of your previous rom and the apks on the new rom wiping dalvik clears the previous apks stored dalvik cache. In most cases you can flash without a problem. But I recommend wiping between rom flashes just to eliminate any potential problems. Flashing something like Thriller over the stock rom you can probably get away with not wiping anything since all the apks are essentially the same. Flashing kernels you don't need to wipe anything. When flashing a rom with a completely different firmware I recommend a full data wipe. Restoring recovery backups such as nandroid require no wiping at all.
Also, wiping dalvik shouldn't affect any of your settings.
Sent from my LG-P920 using Tapatalk
Click to expand...
Click to collapse

so, when i flashed thriller and followed the instructions, did I do a full wipe or not?
I mean if it doest it on its own, and if not, should I do one?

latinohot said:
so, when i flashed thriller and followed the instructions, did I do a full wipe or not?
I mean if it doest it on its own, and if not, should I do one?
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Click to collapse
If you followed the instructions you did a full data wipe. When you do this the dalvik gets wiped as well. To just wipe dalvik look under the Advanced menu in cwm recovery.
Sent from my LG-P920 using Tapatalk

clearing cache
i am using a nand rom in my HD2, and i also want to install another rom via SD in Magldr, but because of kernel issues i cannot load the Rom from SD unless i use the kernal i am advised to use. I am instructed to clear the dalvik and cache, but does this mean that i would lose anything from my current NAND rom? I still want to be able to use that of coarse so i just want to make sure there are no major risks when clearing cache.

ssj5legend said:
i am using a nand rom in my HD2, and i also want to install another rom via SD in Magldr, but because of kernel issues i cannot load the Rom from SD unless i use the kernal i am advised to use. I am instructed to clear the dalvik and cache, but does this mean that i would lose anything from my current NAND rom? I still want to be able to use that of coarse so i just want to make sure there are no major risks when clearing cache.
Click to expand...
Click to collapse
Clearing dalvik and cache wont make you lose anything, used to do it with my shift because I'd flash about 10 zips a day sometimes...
Also when it comes to flashing any ROM I format system data cache wipe dalvik cache and do a factory reset just to be sure nothing from a previous ROM is left over also wipe my SD ext partition when running an a2sd ROM, my question is can I safely manually format the emmc partition of the thrill from the mounts and storage option of cwm
Sent from my LG-P925 using Tapatalk

how to propperly flash anything after already S-off

im just curious and also i want to be able to get an answer to this question. so that noobs like me that have a rooted and s-off device dont get things mixed up.
is truly necesary to do a full wipe ( data, delvik cache, etc.) to flash anything from a simple tweek to something more complex like a custom rom, or kernel?

Yes...it is truly necessary. The only exception being if it's an upgrade for a ROM you're already using. I.e. upgrading WhateverRom 1.4 to 1.5. Even then though a full or partial(cache and dalvik) wipe is usually recommended. You WILL have many problems if you flash a completely different ROM over another one without doing a full wipe.
Edit: proper procedure would be 1. Download the ROM you want 2. Place it onto your external sd card 3. Boot to recovery 4. Full wipe 5. Flash the .zip 6. Reboot 7. Enjoy 8. (optional) Report bugs to the developer in the thread dedicated to the ROM including as much information as you can about your setup, how the bug was achieved and so on
Sent from my HTC Holiday using xda premium

Monkeymannnn said:
Yes...it is truly necessary. The only exception being if it's an upgrade for a ROM you're already using. I.e. upgrading WhateverRom 1.4 to 1.5. Even then though a full or partial(cache and dalvik) wipe is usually recommended. You WILL have many problems if you flash a completely different ROM over another one without doing a full wipe.
Edit: proper procedure would be 1. Download the ROM you want 2. Place it onto your external sd card 3. Boot to recovery 4. Full wipe 5. Flash the .zip 6. Reboot 7. Enjoy 8. (optional) Report bugs to the developer in the thread dedicated to the ROM including as much information as you can about your setup, how the bug was achieved and so on
Sent from my HTC Holiday using xda premium
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Click to collapse
Thanks a lot for your answer, now, to further clarify my questions,
when you are just installing a simple mod, I.E a kernel, to a rom that already feel comfortable with, and you do an delvik and cache wipe? sometimes it really does not writes its properties over the previous kernel, let me explain.
i tried flashing holics kernell which is an non-overclock kernel with an very stable and battery friendly governor. over an more aggressive kernel like the overclocked Faux 123 v007. the results were that my device showed that the kernel installed was the holics but the cpu frequencies that were being run by the governor were more like the previous kernel and the phone was still overclocked although it wasnt supposed to anymore!
is this due to no doing a full data wipe? besides delvik and cache.
also if i was to do a full wipe. wouldnt i have to have some kind of apps back up system planned out. in order to make the phone looked just like it was before the kernel was flashed.?

I'm not that knowledgeable on kernels, but your best bet (afaik) would be to let your ROM boot up for the first time and then flash the new kernel. Titanium Backup is one of if not the best backup program (backs up apps as well as their data among other things). System data such as contacts, texts, etc. can be backed up and restored, but only to the same or very similar ROMs. You're gonna have problems if you restore data from say a touchwiz type interface to sense. Google backs up your contacts and apps anyways if you let it so they'll be restored and re-downloaded once you sign in with your google account.
Sent from my HTC Holiday using xda premium

With any rom or addons always read the devs instructions
Wiping data, cache and dalvik cache is a very safe bet, as for kernels the rom will flash it for you during the installation however if you are wanting to flash a custom kernel other than one in a rom. Just flash the rom and then the kernel.

ronnie498 said:
most devs will let you know what you need to do when flashing their item.
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Click to collapse
That's something I forgot to mention. ALWAYS read the entirety of the original post(s) from the dev. Also read through as much as you can of the thread from there. Nobody appreciates being asked things that were already covered in the thread. Some don't include full instructions, but most will and what they're telling you is what you need to follow.
Sent from my HTC Holiday using xda premium

Here's what I do...
If flashing a whole Rom (even if its just an update) I wipe everything...data, cache and dalvic
If flashing a kernel/apps/tweaks then I just wipe cache and flavorc cache
Those methods have yet to fail me...also, you don't have to let the Rom boot up before flashing a kernel...you can flash a Rom then immediatly flash a kernel (assuming the kernel is compatible with the Rom)
Sent from my HTC Holiday using Tapatalk 2

mg2195 said:
Here's what I do...
If flashing a whole Rom (even if its just an update) I wipe everything...data, cache and dalvic
If flashing a kernel/apps/tweaks then I just wipe cache and flavorc cache
Those methods have yet to fail me...also, you don't have to let the Rom boot up before flashing a kernel...you can flash a Rom then immediatly flash a kernel (assuming the kernel is compatible with the Rom)
Sent from my HTC Holiday using Tapatalk 2
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Click to collapse
THanks, that answers my questions.
i have yet fail to fallow instructions and there have been very little times when i have got my device stuck,
and most of the times when it happened i was able to find the answer of my questions around the forum,
you guys do a great job. :good:

[Q] flashing ARHD 12.1 over 12.0

Hi all,
Sorry I cannot post in ARHD thread due to insufficient post count...so here are my newbie questions:
- I had ARHD 12 installed, now I want to update to 12.1. I know you can flash over 12 without wiping data but the question is do I have to wipe cache in TWRP before flashing 12.1 over 12?
- on ARHD blog, the author said "It is highly recommended that you back up your SD card content to your PC before flashing this ROM. When you are done flashing the ROM, remove the content of SD card and copy back all files from PC". Does it mean I should connect phone to laptop, copy everything inside, flash the ROM, then delete everything? And why is it necessary?
Apologies for bad English.

Erase cache if you want - it's not a requirement. Although I usually do it anyway..
Copying files to your PC thing your talking about was probably from the ROM moving from 4.1.2 to 4.2.2. Nothing for you to worry about since you're already on 4.2.2.
Just flash it..
Sent from my HTC One using xda premium

redbull123 said:
Erase cache if you want - it's not a requirement. Although I usually do it anyway..
Click to expand...
Click to collapse
thanks for your answer. I would probably wipe cache and dalvik cache just incase. However would I lose anything by wiping these? phone settings, accounts, app settings...?

XkWiZiT said:
thanks for your answer. I would probably wipe cache and dalvik cache just incase. However would I lose anything by wiping these? phone settings, accounts, app settings...?
Click to expand...
Click to collapse
You wouldn't lose anything of importance - just your caches. They will re-appear on reboot.

i flashed 12.1 on 12 and everything is great, i did't wipe cache or anything else. U can backup your files just in case

[Q] Tablet is acting strange

Hi,
I've been using galaxy tab 8.9 with custom ROMs for more than a year and a half now, and sometimes it was acting strange, like flickering dialogs and crashes. Usually this meant an unstable ROM or just cache wasn't cleared when a new ROM was installed. And it was stable for some time, till I did a reset. Now no ROM is stable any more in addition to this, the battery sometimes says it is empty, but after restart it is back to normal status. I tried number of ROMs without luck, all are flickering lately which must mean it is not ROMs fault.
I am running out of ideas what to do with this tablet, so I'm asking if you guys have any suggestions, what else can I do to fix it.
NOTE: when installing a new ROM, I always did it with CWM recovery from internal storage with data, cache, dalvik wipe and factory reset.
regards, Daniel

danizmax said:
Hi,
I've been using galaxy tab 8.9 with custom ROMs for more than a year and a half now, and sometimes it was acting strange, like flickering dialogs and crashes. Usually this meant an unstable ROM or just cache wasn't cleared when a new ROM was installed. And it was stable for some time, till I did a reset. Now no ROM is stable any more in addition to this, the battery sometimes says it is empty, but after restart it is back to normal status. I tried number of ROMs without luck, all are flickering lately which must mean it is not ROMs fault.
I am running out of ideas what to do with this tablet, so I'm asking if you guys have any suggestions, what else can I do to fix it.
NOTE: when installing a new ROM, I always did it with CWM recovery from internal storage with data, cache, dalvik wipe and factory reset.
regards, Daniel
Click to expand...
Click to collapse
Do you ever wipe the system partition?

upconvert said:
Do you ever wipe the system partition?
Click to expand...
Click to collapse
Agree. In TWRP, a factory reset only wipe data, cache and dalvik cache. You have to manually format system. A clean install requires to wipe system, data, cache and dalvik-cache.
---------- Post added at 08:18 AM ---------- Previous post was at 08:17 AM ----------
danizmax said:
Hi,
I've been using galaxy tab 8.9 with custom ROMs for more than a year and a half now, and sometimes it was acting strange, like flickering dialogs and crashes. Usually this meant an unstable ROM or just cache wasn't cleared when a new ROM was installed. And it was stable for some time, till I did a reset. Now no ROM is stable any more in addition to this, the battery sometimes says it is empty, but after restart it is back to normal status. I tried number of ROMs without luck, all are flickering lately which must mean it is not ROMs fault.
I am running out of ideas what to do with this tablet, so I'm asking if you guys have any suggestions, what else can I do to fix it.
NOTE: when installing a new ROM, I always did it with CWM recovery from internal storage with data, cache, dalvik wipe and factory reset.
regards, Daniel
Click to expand...
Click to collapse
Try flashing the original firmware via odin.

iZLeeP said:
Try flashing the original firmware via odin.
Click to expand...
Click to collapse
Flashing original firmware would be my last resort. Is there any difference between odin and CWM flashing?

danizmax said:
Flashing original firmware would be my last resort. Is there any difference between odin and CWM flashing?
Click to expand...
Click to collapse
Of course. Flashing original firmware via odin brings back the original setup that came with the tab out of the box. I just don't remember if it will delete the contents of internal sd card. In any case, you can flash original firmware thru CWM as I always do, though I only flash boot and system images I modified in Kitchen. It will still be stock but only that it has been debloated, rooted, busybox installed, init.d enabled, and some system apps replaced.
Just remember that when flashing ROMs via CWM do a factory reset (wipe data, cache, dalvik-cache). In addition to the wipe, the rom.zip itself formats the system partition prior to flashing.

upgrading to Nougat, trouble replacing old kernel

Apologies for duplicating this post but the original forum was apparently the wrong spot for this.
I need either some pointers or a reference to a how-to, if you please.
My Nexus 6 is currently running Pure Nexus 6.0.1-2060821-official, security patch 8/5/2016 with ElementalX kernel 3.10.40-ElementalX-N6-3-20.
I've updated Pure Nexus before through TWRP and all went well, but those efforts never involved updating the kernel too. I've attempted to flash the new kernel, the rom and the google apps, but the phone goes into a never ending boot effort and it's a tussle getting back to recovery mode as it tends to boot loop. The flashes are preceded by clearing Delvik and cache and cleared again after the flash.
Is the order of flashing off or perhaps not enough clearing of other items such as system? Or is a factory reset needed?
Kind of lost on this one and can't seem to string together enough search terms to find help specific to the problem.
Any help would be appreciated.

The kernel is most likely not updated to work with the rom. Each rom comes with its own kernel so you really don't have to flash a new one. I would flash the rom and gaps and see what happens. Leave the kernel out of it for now. You have to remember that not all kernels work on all roms. Many roms are making it so only their kernel works properly.

zelendel said:
The kernel is most likely not updated to work with the rom. Each rom comes with its own kernel so you really don't have to flash a new one. I would flash the rom and gaps and see what happens. Leave the kernel out of it for now. You have to remember that not all kernels work on all roms. Many roms are making it so only their kernel works properly.
Click to expand...
Click to collapse
Still no-go. Freshly downloaded purenexus_shamu-7.1.1-20170215-OFFICIAL and Full_Dynamic_GApps-7.1.x-20161215, checked the MD5s, and flashed both after cache/Dalvik. Still got the same 4-color bouncing dots. Let it run like that for about 40 minutes before getting back into recovery.
Ran the same flash but this time also wiped system. Same result.
Is 40 minutes enough time? Impatience maybe?
Now back to original 6.0.1, PureNexus 6.0.1-20160821 and 3.10.40-ElementalX-N6-3.20 kernel.
Any ideas?

jlfesslerkc said:
Still no-go. Freshly downloaded purenexus_shamu-7.1.1-20170215-OFFICIAL and Full_Dynamic_GApps-7.1.x-20161215, checked the MD5s, and flashed both after cache/Dalvik. Still got the same 4-color bouncing dots. Let it run like that for about 40 minutes before getting back into recovery.
Ran the same flash but this time also wiped system. Same result.
Is 40 minutes enough time? Impatience maybe?
Now back to original 6.0.1, PureNexus 6.0.1-20160821 and 3.10.40-ElementalX-N6-3.20 kernel.
Any ideas?
Click to expand...
Click to collapse
You are doing a full wipe right? Wiping system and data before flashing?
Also encryption could be an issue. If your device in encrypted or the kernel did not remove the force encryption flag. That could take awhile as well.

jlfesslerkc said:
Still no-go. Freshly downloaded purenexus_shamu-7.1.1-20170215-OFFICIAL and Full_Dynamic_GApps-7.1.x-20161215
Click to expand...
Click to collapse
Get the Feb 15 GApps too instead of the Dec 15 GApps. Don't use old GApps.
https://forum.xda-developers.com/android/software/gapps-dynamic-gapps-t3487192
Also make sure that the GApps are 7.1.x and not 7.x.x or you get a SDK mismatch. What does the recovery log show?

Pkt_Lnt said:
Get the Feb 15 GApps too instead of the Dec 15 GApps. Don't use old GApps.
https://forum.xda-developers.com/android/software/gapps-dynamic-gapps-t3487192
Also make sure that the GApps are 7.1.x and not 7.x.x or you get a SDK mismatch. What does the recovery log show?
Click to expand...
Click to collapse
Got the Feb GApps, wiped Dalvik and cache... this time I let it run for a bit over an hour in case the encryption was an issue. There's a little over 19 GB in files. I figured an hour would be enough but no luck. Had to recover again from backup.
TWRP gives 5 items that can be wiped, Dalvik, System, data, Internal Storage and Cache. I was of the understanding that data pertained to user data (photos, notes, etc). Most all of that is backed up but I'm unclear on what needs wiping for this Nougat upgrade. When I wiped system, it didn't seem to help - although I was using the older GApps at that point. I've seen documentation that says to wipe these items at the outset and others that suggest after the flash is complete. Both? Which ones?
I don't want to resort to drastic measures if it's something simple that I've missed.

Needs Nougat bootloader and latest radio--flash in TWRP. This allows flashing N ROMs while will still work with all MM or even 5.1 ROMs
http://batakang.com/ftp/devs/mhous33/shamu/bootloaders/shamu_bootloader_moto-apq8084-72.01.zip
http://batakang.com/ftp/devs/mhous33/shamu/7.1.1/shamu_baseband_D4.01-9625-05.44+FSG-9625-02.115.zip

jlfesslerkc said:
Got the Feb GApps, wiped Dalvik and cache... this time I let it run for a bit over an hour in case the encryption was an issue. There's a little over 19 GB in files. I figured an hour would be enough but no luck. Had to recover again from backup.
TWRP gives 5 items that can be wiped, Dalvik, System, data, Internal Storage and Cache. I was of the understanding that data pertained to user data (photos, notes, etc). Most all of that is backed up but I'm unclear on what needs wiping for this Nougat upgrade. When I wiped system, it didn't seem to help - although I was using the older GApps at that point. I've seen documentation that says to wipe these items at the outset and others that suggest after the flash is complete. Both? Which ones?
I don't want to resort to drastic measures if it's something simple that I've missed.
Click to expand...
Click to collapse
What TWRP version? Old one cause problems on newer ROMS. Newest is 3.1.0, but 3.0.3 or 3.0.2 should be ok.
Wipe everything - /system, /data, /cache. /dalvik. Do NOT wipe Internal Storage (camera photos, downloads, etc.) before flashing. Data is usually app data, so make a nandroid first to save it, but app data can usually be restored with Titanium Backup or Google will restore it on setup. Just do not restore any system data.
Bootup on clean flash does take time, but normally no more than 20-25 minutes.

Try reverting to stock
Install stock firmware using adb

TWRP version might be the glitch.... Mine reports 2.8.5.0 in recovery mode. I'll update to the latest and retry after wiping all but internal storage. If that fails, I'll flash the boatloader and radio.
Once more into the breach.

jlfessler said:
TWRP version might be the glitch.... Mine reports 2.8.5.0 in recovery mode. I'll update to the latest and retry after wiping all but internal storage. If that fails, I'll flash the boatloader and radio.
Once more into the breach.
Click to expand...
Click to collapse
Hi... Save your internal storage before processing. Just in case... TWRP 2.8.5.0 is pre nougat and incompatible.

jlfessler said:
TWRP version might be the glitch.... Mine reports 2.8.5.0 in recovery mode. I'll update to the latest and retry after wiping all but internal storage. If that fails, I'll flash the boatloader and radio.
Once more into the breach.
Click to expand...
Click to collapse
You should really update the bootloader/radio to the latest once you update the TWRP. Updating the bootloader/radio will not affect your internal storage.

Pkt_Lnt said:
What TWRP version? Old one cause problems on newer ROMS. Newest is 3.1.0, but 3.0.3 or 3.0.2 should be ok.
Wipe everything - /system, /data, /cache. /dalvik. Do NOT wipe Internal Storage (camera photos, downloads, etc.) before flashing. Data is usually app data, so make a nandroid first to save it, but app data can usually be restored with Titanium Backup or Google will restore it on setup. Just do not restore any system data.
Bootup on clean flash does take time, but normally no more than 20-25 minutes.
Click to expand...
Click to collapse
Wiping system, data, cache and Dalvik seems to have gotten me to Nougat but apparently root did not come along for the ride. Wasn't expecting that. Is that par for the course?

jlfesslerkc said:
Wiping system, data, cache and Dalvik seems to have gotten me to Nougat but apparently root did not come along for the ride. Wasn't expecting that. Is that par for the course?
Click to expand...
Click to collapse
yup
Item 1.8 and 1.9 here

Pkt_Lnt said:
yup
Item 1.8 and 1.9 here
Click to expand...
Click to collapse
Thanks. 1.9 refers to SuperSU which is what I used earlier.
Also I take it reinstalling TitaniumBackup will then let me restore the apps. Still on track?

jlfesslerkc said:
Thanks. 1.9 refers to SuperSU which is what I used earlier.
Also I take it reinstalling TitaniumBackup will then let me restore the apps. Still on track?
Click to expand...
Click to collapse
That is what Titanium Backup (and Restore) does, yes.