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When I first installed KatKiss 6, I had to unpack and repack kernels in order to try out different combinations of zImage, ramdisk files, and modules. Many people may not want to go through the trouble, but there is an easier way to do that.
So, why do we want to try different combinations of zImage, ramdisk files, and modules? To see if performance is better could be an incentive, but the main reason is that sometimes a different combination of zImage, ramdisk files, and modules may fix things that are not working properly. For example, with cm kernel, GPS can't get good signals in the PAC ROM 5.1.1 I compiled. The problem is solved by using ramdisk of Cyanogenmod, and zImage and modules of Grimlock kernel 5.1.1.
Actually, @_that mentioned the two ways that can accomplish this back in January, but I went with the more complicated one because I had little knowledge of programming. I finally figured out how to do that the easier way recently.
The downside is that you must use a zImage supporting preinit in order to load ramdisk files that are not packed in the kernel. that kernel and Grimlock kernel both support preinit.
If you don't use kexecboot, zImage will always be from the kernel you installed for internal ROM. If it's a ROM2SD installation, the ramdisk files will be from the kernel you choose during ROM2SD installation. The modules are usually copied from internal during ROM2SD installation.
If you want to change zImage, then you have to flash a different kernel to /boot partition. If you want to change ramdisk file for ROM2SD installation, then you need to first delete the boot/ folder on the /system partition of the micro SD card. Then you can flash the kernel containing the ramdisk files between rom2sd1.zip and rom2sd2.zip following the method by @_that. Alternatively, you can also use the ones in this post. The differences are that the updated scripts from ZOMBi-POP will copy modules from internal /system, instead of using the ones packed by @_that.
If you want to use that kernel with KatKiss 6, you have to load ramdisk files from KatKernel to use with zImage of that kernel. To load different ramdisk files for a ROM installed on internal storage, you need to revise '20detect-microsd' file in internal /system/boot/preinit.d/ , which will copy ramdisk files from internal /system/boot/ramdisk to /. You can download the one I used, which is attached. The following lines are added to the original file.
Code:
else
# copy ramdisk files from internal /system/boot/ramdisk to /
$BB cp -a /system/boot/ramdisk/* / || echo "failed to copy ramdisk files from /system/boot/ramdisk"
You certainly need to extract the ramdisk files to internal /system/boot/ramdisk/ . To do that, you can use the attached extract ramdisk to internal system.zip. Just replace the 'boot.blob' inside with the one you'd like to use. Basically, it's the rom2sd2.zip from @_that, but without the scripts doing revision for ROM2SD.
At least for some ROMs, you can see performance gain with F2FS /cache. If you want to try to see if F2FS /cache works better for you. You can convert /cache to F2FS with TWRP 2.8.+. Just go to Wipe->Advanced Wipe, select Cache, and Change file system to F2FS. You also need to revise 'fstab.cardhu' in /system/boot/ramdisk/ for all the ROMs you are running. Just replacing the line for /cache with the following one
Code:
/dev/block/mmcblk0p2 /cache f2fs noatime,nosuid,nodev,errors=panic wait,encryptable=footer
Alternatively, you can use attached extract ramdisk to internal system f2fs cache .zip or rom2sd2 f2fs cache.zip when extracting the ramdisk files to internal or ROM2SD /system. The following line is added to 'extract-ramdisk.sh' so that 'fstab.cardhu' will be revised during extraction.
Code:
sed -i '/mmcblk0p2/{;s/ext4/f2fs/;s/barrier=.,//;s/nodiratime,//;s/noauto_da_alloc,//;s/nomblk_io_submit,//;}' $f
I am able to use different zImages for internal and external ROMs and choose which one to boot with kexecboot. If someone is interested in how to set that up, please just ask in the comments.
There is a 'boot.blob' (I beleive it's for PAC511) in 'extract ramdisk to internal system f2fs cache .zip' You need to replace it with the one you'd like to use, or delete it and flash your kernel before flashing this zip.
HI everyone i need your help to develop a kernel with adhoc support for gt s7270(logan)
I followed the instruction:
1) I downloaded the kernel from the repo in git hub
2) I do the modifications in broadcom wifi driver to support adhoc mode
3) I compiled the kernel for my device and now i have the zimage.
Now because i do not how to create a ramdisk image I take the zip of rom(cm11) and decompresed the boot.img and split into ramdisk and zimage.
Now i ovewrite the zimage, and i repack the boot img, all this I did with the application that I found in xda(https://forum.xda-developers.com/showthread.php?t=2319018)
Now when i flashed the zip that constains the new zimage i get a boot loop. Can you help me and tell what i did wrong?
I builded custom kernel for my Oneplus lemonade (A/B 2 slot)
I got "Image" & "Image.gz" file, how can i put it in boot.img
MURSHIG said:
I builded custom kernel for my Oneplus moo lemonade (A/B 2 slot)
I got "Image" & "Image.gz" file, how can i put it in boot.img
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I have no AIK , just mkbootimg python vers from official Google repo, im executing ./unpackimg.py --boot_img boot.img --out out
in out directory there is -
file kernel - uncompressed kernel
file ramdisk - uncompressed ramdisk
Hello,
I'm just getting into Android, and I've been messing around with boot.img with Magisk.
The boot.img that I'm specifically looking at is Pixel 6a.
I used `magiskboot unpack boot.img`, but I only got a kernel file.
Now, I'm wondering where the ramdisk.cpio. From what I read, ramdisk determines what to mount and whatnot.
Even without a ramdisk, I can fastboot flash boot boot.img it to my device and it will still work.
If there is no ramdisk in boot.img, then how does the device know what to mount or what the file hierarchy is when I flash it?
If the stock boot.img doesn't have a ramdisk, does not mean I have to generate my own?
Thanks!
init is on system, no ramdisk required.
https://source.android.com/docs/core/architecture/partitions/system-as-root#sar-partitioning
alecxs said:
init is on system, no ramdisk required.
https://source.android.com/docs/core/architecture/partitions/system-as-root#sar-partitioning
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does that mean if I do include ramdisk.cpio, it overrides the one on system?
Yes, if you modify the kernel so ramdisk is extracted and processed (that's what Magisk does)
alecxs said:
Yes, if you modify the kernel so ramdisk is extracted and processed (that's what Magisk does)
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Click to collapse
Thank you so much for the link. I read up on it, and as you said, boot.img just carries a kernel file and ramdisk is in system.img.
It looks like you can also unpack, modify, and repack system.img and flash it onto pixel devices, so do you know why Magisk decided to create ramdisk.cpio and repack it into boot.img when it could have modified system.img? Is it because boot.img has a kernel file?
Thanks
Magisk also mods the DTB from "skip_initramfs" to "want_initramfs".
drunk_santa said:
It looks like you can also unpack, modify, and repack system.img and flash it onto pixel devices, so do you know why Magisk decided to create ramdisk.cpio and repack it into boot.img when it could have modified system.img?
Click to expand...
Click to collapse
Because Magisk is systemless-root method
https://topjohnwu.github.io/Magisk/boot.html
Hi, I'm not sure if I have to flash the kernel partition with the kernel zImage or install the kernel in order to apply it? I am going to recompile the kernel with the swap option enabled, so it's basically a small change. Is there anything that I should know before I do this? How do I flash this? Is odin allright? BTW I have seen that the A2N kernel has a zip rom which is being installed from the cwm recovery. It has the kernel zImage placed as boot.img, in the root of the zip. It's strage to me, because I don't have boot.img in the partition mounted on / on the stock kernel, so where does it go? Or is the modified kernel being swapped with the stock one during boot-time?
zielonykid1234 said:
Hi, I'm not sure if I have to flash the kernel partition with the kernel zImage or install the kernel in order to apply it? I am going to recompile the kernel with the swap option enabled, so it's basically a small change. Is there anything that I should know before I do this? How do I flash this? Is odin allright? BTW I have seen that the A2N kernel has a zip rom which is being installed from the cwm recovery. It has the kernel zImage placed as boot.img, in the root of the zip. It's strage to me, because I don't have boot.img in the partition mounted on / on the stock kernel, so where does it go? Or is the modified kernel being swapped with the stock one during boot-time?
Click to expand...
Click to collapse
Convert your kernel into an Odin flashable zip using 7zip with its highest level of compression in tar format, make sure the file is converted into a .tar file or a .tar.md5 then flash that file via Odin in the AP or PDA slot. You might need to use a modified version of Odin.