How to specify custom partition layouts? - G1 Q&A, Help & Troubleshooting

I just saw an interesting thread in the development section that explains an alternative to the Death SPL. The method there lets you flash ANY rom on any SPL, but I dont really understand how it works.
The thread can be found here: http://forum.xda-developers.com/showthread.php?t=704560
So basically, you shrink the cache partition to allow for more room for the actual ROM(which partition does that go in?)?
To do this do we edit the boot.img in the ROM update.zip? What else do we do?
Could someone explain this in a way a 9th grader could understand?

kingkurry said:
Could someone explain this in a way a 9th grader could understand?
Click to expand...
Click to collapse
Take file by firerat, flash file. omgroflpartitons.
If you don't understand the instructions as they are, wait for it to be perfected before you try anything. This will probably end up being integrated into releases that need it, so you don't need to worry about the specifics at the moment.

Will that patch file work for all ROMs. He said its only been tested with CyanogenMod 5. And I want to understand what im doing, not just do it without thinking about it...

Also, does the recovery patcher decrease the size of the partition that holds the recovery image?
Does it permanently change the size of the recovery partition?
When you flash a ROM, what partition is it being flashed too? Is this the one being increased in size?
What does the boot.img in an update.zip package hold, and is that copied to the boot partition?
Sorry but my curiosity is killing me

OK well to break it down we have 6 partitions on the internal memory:
Misc - Here be dragons
Recovery - Contains recovery system (+seperate recovery kernel) - recovery.img lives here
Boot - Contains kernel & important initialization stuff - boot.img lives here
-------------
System - Contains the whole android system (the "ROM", if you like).. everything else from an update.zip apart from the boot.img
Cache - Used by system and recovery for temporary storage
Userdata - Contains all personal data, downloaded apps, settings etc.
The first three partitions must be left at the default size so don't worry about them.
What this patch does is pass a command to the kernel which remaps the 3 large partitions at boot time. Since we're flashing system images from recovery, we also need to pass the same command to the recovery kernel before attempting to flash the main system, or we'd be writing to one place then telling the kernel to look for it in another.. bad idea.
This method allows any partition setup you like, but the most useful at the moment (and this is the way firerat has set up his scripts to suit cm5) is to make the /system partition just the right size for the "ROM" with a bit of breathing space, make the /cache partition a minimal size for the recovery system to use, then have /userdata fill the remaining space so we can load it up with apps. Since we've reduced cache to a minimal size, it's redirected at boot time to a place on the sdcard instead.. this give us maximum space to divide between /system and /data with no wastage.
Does that help at all..?

Thanks dude. That does help a lot.
Just wondering though, how much breathing space do u need in the system partition?
What does the recovery system use the cache partition for and how do we know what "a minimal size for the recovery system to use" is?
Is it possible to reduce the userdata partition to the minimum possible size a partition can be(if i recall correctly it was 128kb) and use an ext partition on your SD card instead?
If we shrink the Cache partition a lot, does this mean we have to use linux swap to compensate for the lowered amount of cache?
Also do we have to remap the partitions every time we flash a new ROM?
And what are the "dragons"?

kingkurry said:
And what are the "dragons"?
Click to expand...
Click to collapse
He's saying that it's just there. There could be anything from nothing there to a text document containing the ingredients to the cure of AIDs.

Well what about every thing else? Can you guys help me with that? Also what is the total size of all 3 of the big partitions combined?

Related

[Q] Partition sizes at Flash

I need to resize my /system partition on my phone since its out of space. It seems like the only way I'll be able to do it (regardless of what I do), will be to reflash my phone and make sure the partition is large enough this time.
My question is: In the process of flashing, how are partition sizes for data, system, cache, etc. determined? I notice in Odin3 there is a box for "repartition" so I assume that somewhere there must be a way to define the sizes.
Thanks

[q] urgent help needed!!!!

Hi folks,
I have been using G1 for 6-7 months and had never faced this frigging problem ...i think it all started when i tried to flash an HTC sense ROM!! I did all the things as instructed for flashing, but it dint work.. Then i reverted to Gingerbread(version-2.3.4) which i was using before. Though the ROM worked i was sickened to see my internal storage memory as it had only 17.75MB left!!! . My phone has now Total space just 17.75MB out of which the available space is only 6.70MB!! .. Here is a screenshot of my phone storage-
While flashing a swap size of 32 was kept and sd-ext was given 512MB
Any idea how to recover from this frigging problem?????
thanx...
Remove cMTD ...
Flash the following File, reboot into fastboot, do a "fastboot erase system -w" and reinstall your ROM. This should help ...
Thnx for that quick reply.. .. by 'fastboot' did you mean 'recovery mode'.. I flashed the file and then manually wiped all the data's,dalvik-cahce and other things.. is that enough?
@ AndDiSa It worked .. that was frigging awesome man!! thanx a lot.. now i have 92MB free.. can you please explain me what the problem really was?
haha your problem was that you flashed a custom MTD partition (most likely 145 2) on your device for that sense rom.. but when you do that you need to flash fr-boot after you flash any other rom while you still have that partition.. but since you went back to a diff rom you thought you didnt need the fr-boot lol, so your phone didnt have the correct amount of mb..
When you wipe your data and all that it does NOT remove the custom mtd... thats why you needed to flash the FR-Remove file!! to remove the MTD partition... which basically put your device back how it was when first rooted... 90 2 ... thats the stock partition size for a g1
So long story short your device will be fine and you can re try to flash that sense rom or do anything you want... just be sure to remove a custom mtd if you flashed one for a rom... and plan to change roms.. unless you switch to a rom that also needs a mtd partition.. than you dont have to flash remove.. just flash the boot file after flashing rom. lol sorry if that was confusing..
ldrifta said:
haha your problem was that you flashed a custom MTD partition (most likely 145 2) on your device for that sense rom.. but when you do that you need to flash fr-boot after you flash any other rom while you still have that partition.. but since you went back to a diff rom you thought you didnt need the fr-boot lol, so your phone didnt have the correct amount of mb..
When you wipe your data and all that it does NOT remove the custom mtd... thats why you needed to flash the FR-Remove file!! to remove the MTD partition... which basically put your device back how it was when first rooted... 90 2 ... thats the stock partition size for a g1
So long story short your device will be fine and you can re try to flash that sense rom or do anything you want... just be sure to remove a custom mtd if you flashed one for a rom... and plan to change roms.. unless you switch to a rom that also needs a mtd partition.. than you dont have to flash remove.. just flash the boot file after flashing rom. lol sorry if that was confusing..
Click to expand...
Click to collapse
... that was very confusing.
The base you explained correctly: There was still installed the cMTD patch which gave you a custom partition layout with a big /system partition, but a very small /data partition.
This partition layout is defined by boot img parameters, as in recovery, as for the ROM. Most new ROMs (especially GB-ROMs) detect cMTD automatically, i.e. it's sufficent to patch the recovery image while the boot image is patched automatically when installing the ROM.
When you switch between ROMs the partition layout will be kept, as it was for you when you switched back to the "old" GB-ROM. To return to the "standard" layout (which is defined by the SPL you have installed on your phone), you either have to flash a "clean" recovery, or to remove the cMTD layout with the file I gave you.
If you are more interested in cMTD, in my signature you can find a link to the appropriate thread ...
AndDiSa said:
... that was very confusing.
The base you explained correctly: There was still installed the cMTD patch which gave you a custom partition layout with a big /system partition, but a very small /data partition.
This partition layout is defined by boot img parameters, as in recovery, as for the ROM. Most new ROMs (especially GB-ROMs) detect cMTD automatically, i.e. it's sufficent to patch the recovery image while the boot image is patched automatically when installing the ROM.
When you switch between ROMs the partition layout will be kept, as it was for you when you switched back to the "old" GB-ROM. To return to the "standard" layout (which is defined by the SPL you have installed on your phone), you either have to flash a "clean" recovery, or to remove the cMTD layout with the file I gave you.
If you are more interested in cMTD, in my signature you can find a link to the appropriate thread ...
Click to expand...
Click to collapse
lol sorry im not really sure how the mtd partitions really work.. i just knew i had to use it at one point and i read up a little about it but that was a while ago... so i kinda forgot the exact details.. thank you for clearifying!!

[Q] The wisdom of formatting the system partition

I'm getting ready to update my old ParanoidAndroid (with CWM v5.5.0.4) with the CarbonRom.
I've backed up all kinds of logs, settings, and data that I think I may want to restore with the new rom.
I've also made a CWM backup (although of course I hope not to use it).
My question is - should I format the system partition (from CWM, Mounts & Storage option) before flashing the new rom?
I've seen people say emphatically that to get a clean install you need to do this.
Yet I've seen other's write just as insistently that you should NOT format the system partition. Do they say this because it is too dangerous? If I format the system partition and then for some reason the new rom won't load, does that mean my CWM is wiped out, making it difficult to recover?
I think I do want the system format because I don't want a bunch of old files hanging around ... but I want to make sure this is not too dangerous.
I've also seen others who recommended also formating the boot partition. Is there any value in that? Sounds even more dangerous ... no?
~Paul
pmennen said:
I'm getting ready to update my old ParanoidAndroid (with CWM v5.5.0.4) with the CarbonRom.
I've backed up all kinds of logs, settings, and data that I think I may want to restore with the new rom.
I've also made a CWM backup (although of course I hope not to use it).
My question is - should I format the system partition (from CWM, Mounts & Storage option) before flashing the new rom?
I've seen people say emphatically that to get a clean install you need to do this.
Yet I've seen other's write just as insistently that you should NOT format the system partition. Do they say this because it is too dangerous? If I format the system partition and then for some reason the new rom won't load, does that mean my CWM is wiped out, making it difficult to recover?
I think I do want the system format because I don't want a bunch of old files hanging around ... but I want to make sure this is not too dangerous.
I've also seen others who recommended also formating the boot partition. Is there any value in that? Sounds even more dangerous ... no?
~Paul
Click to expand...
Click to collapse
You can format system,data, internal storage and cache without any worries if you are on PA rom read install instructions in carbon rom thread after or before.
Sent from my GT-N7000 using Tapatalk

Question about userdata.img and cache.img

I'll make this one quick, so I know the userdata.img that comes with stock images is just a blank image that's sole purpose is to format your userdata partition for you, and that you can use fastboot format userdata for the same result, however is it the same deal with the cache.img file? Is the cache file just a blank image used for formatting the cache partition of your device or does it actually contain some data that the device needs to function? Thanks!
I have yet to flash either and have had no problems. I wipe both through twrp before booting up for the first time.
There is nothing of importance in either.
danarama said:
There is nothing of importance in either.
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Click to collapse
So in this sense, formating or erasing the cache is the same effect as flashing the cache.img?
H4X0R46 said:
So in this sense, formating or erasing the cache is the same effect as flashing the cache.img?
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Click to collapse
Yes and no.. Sort of.
The image itself, I don't really know why it exists. When you fastboot flash those images, it does a format first. Actually flashing the image afterwards has no benefit.
They could just put the format commands in the flash-all script. Perhaps they've done it for those who don't use the script to encourage them to format by flashing the image. Only thing I can think of. Or maybe those images are big enough that they wrote 0 byte data over existing data blocks that exist after the format to make them more secure, because really, a format or erase doesn't destroy data. It just makes it inaccessible by the average user. So it could be that they're overwriting a small section of data in the partition as that is the only way to destroy data.
Anyway, it should be rare that you need to format those partitions..
Formatting just erase allocation table, flash an empty.img overwrite and really cleans the data.. I think..
_____________________________________Read more write less and be smart
danarama said:
Yes and no.. Sort of.
The image itself, I don't really know why it exists. When you fastboot flash those images, it does a format first. Actually flashing the image afterwards has no benefit.
They could just put the format commands in the flash-all script. Perhaps they've done it for those who don't use the script to encourage them to format by flashing the image. Only thing I can think of. Or maybe those images are big enough that they wrote 0 byte data over existing data blocks that exist after the format to make them more secure, because really, a format or erase doesn't destroy data. It just makes it inaccessible by the average user. So it could be that they're overwriting a small section of data in the partition as that is the only way to destroy data.
Anyway, it should be rare that you need to format those partitions..
Click to expand...
Click to collapse
Yea it really is kind of confusing that they add these blank images, would it be a safer bet in this case to use the erase command as opposed to format? Or is it a better idea to just flash these blank images? They really made it confusing by adding them. I also have a 64GB nexus 6, so after flashing the userdata.img, it shows I only have 32GB! It requires a factory reset that, as you know, takes AGES on this device! In short, should the format command be used in more rare circumstances as opposed to erase or using the img file?
Use format to fix your issue. The images are known to cAuse this.

/system file system question

Hey there.
In twrp I can't change my system partition file system to F2FS. To do it, I enter twrp and do the "normal" steps (wipe, advanced, change to f2fs).
TWRP says it changed but if I perform the same steps the file system type remains ext4.
Is this supposed to be like this?
You cannot format the system
It's really not practical to change the filesystem of /system since it's distributed as an image and not as files. You theoretically could do it, but it would be a lot of work and you'd have to redo it from scratch every time you updated your ROM. Also, you wouldn't get most of the benefits of f2fs since you'd almost never be writing to it.

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