[HOW TO]Get Base Address from boot.img - Android

Hello guys,
What I did
I just create a way to
extract the base address information from boot.img(the image made from mkbootimg).
Base address is very important when call mkbootimg to make image.
Here is the link how to unpack repack image
That method is very useful when there is no config information from kernel img(Like my situation)
The concept of it
I read the source code of mkbootimg.c, that's the git of it
And find that the all the information of kernel address, ramdisk address is contained in the header of boot.img,
and the base address can be calculate from them.
then you don't need to look for the base address information from the config.gz,
and just need one official rom to get the information.
What I bring
In attachment, It is the small tool I made to get the information from boot.img(include calculate the base address)
And Here is the source code of it
How to Use it
It needs to be run under linux or cygwin.
Go into the directory contain the tool, and type command
Code:
./GetImageInfo Boot_Image_Path
I just make the code today, so maybe there are some defect.
If you have some suggestion, please let me know.
Thank you very much

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Compiled it for arm and tried it out on my image. It's reading base address as 0 and reports that the header is not correct so it cannot give me the base address. However, my base address is 0x80600000. Could you explain?

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SHM said:
Compiled it for arm and tried it out on my image. It's reading base address as 0 and reports that the header is not correct so it cannot give me the base address. However, my base address is 0x80600000. Could you explain?
Click to expand...
Click to collapse
Hello, if you see the output is "Image Header is not in correct format" or "Error Header Information:"
It means there are some data corruption in the header part.
Maybe it hasn't assign kernel_address or ramdisk_addr correctly.
Here is the right relation ship between every address
1, kernel_address < ramdisk_address
2, ramdisk_address - kernel_address == ramdisk_offset - kernel_offset
3 kernel_offset = 0x00008000 ramdisk_offset = 0x01000000
4, Conclusion: base_address = ramdisk_address - ramdisk_offset;
Any of Condition 1 or 2 or 3 is not met, it means the header is not in a correct form.
You can give me your image, I can check it for you.

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huuu said:
Hello, if you see the output is "Image Header is not in correct format" or "Error Header Information:"
It means there are some data corruption in the header part.
Maybe it hasn't assign kernel_address or ramdisk_addr correctly.
Here is the right relation ship between every address
1, kernel_address < ramdisk_address
2, ramdisk_address - kernel_address == ramdisk_offset - kernel_offset
3 kernel_offset = 0x00008000 ramdisk_offset = 0x01000000
4, Conclusion: base_address = ramdisk_address - ramdisk_offset;
Any of Condition 1 or 2 or 3 is not met, it means the header is not in a correct form.
You can give me your image, I can check it for you.
Click to expand...
Click to collapse
Here you go. This isn't my stock recovery image. It's my personal TWRP build for my device but the offsets are no different between the two. I'm curious to learn more about your logic on all this.

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Also, my recovery/boot uses non standard base, and ramdisk offset as typically seen in mkbootimg.c.

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SHM said:
Here you go. This isn't my stock recovery image. It's my personal TWRP build for my device but the offsets are no different between the two. I'm curious to learn more about your logic on all this.
Click to expand...
Click to collapse
Let me check you image first.
I learned all those logic from the source code of mkbootimg.
But I am not able to see the source code of it so far, I can post it later after I get home.

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SHM said:
Also, my recovery/boot uses non standard base, and ramdisk offset as typically seen in mkbootimg.c.
Click to expand...
Click to collapse
That's the output of the information
kernel size = 0x5905a0
kernel address = 0x80608000
ramdisk size = 0x56c7bd
ramdisk address = 0x81c08000
second size = 0x0
second address = 0x81500000
tag address = 0x80600100
page size = 0x800
Actually, Kernel address is ok,
The problem is on Ramdisk Address.
base_address == kernel_address - kernel_offset == ramdisk_address - ramdisk_offset

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huuu said:
That's the output of the information
kernel size = 0x5905a0
kernel address = 0x80608000
ramdisk size = 0x56c7bd
ramdisk address = 0x81c08000
second size = 0x0
second address = 0x81500000
tag address = 0x80600100
page size = 0x800
Actually, Kernel address is ok,
The problem is on Ramdisk Address.
base_address == kernel_address - kernel_offset == ramdisk_address - ramdisk_offset
Click to expand...
Click to collapse
Yea, in mkbootimg.c the standard ramdisk offset is 0x01000000 but my recovery and boot images uses non standard ramdisk offsets. It uses, 0x01608000.
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SHM said:
Yea, in mkbootimg.c the standard ramdisk offset is 0x01000000 but my recovery and boot images uses non standard ramdisk offsets. It uses, 0x01608000.
Sent from my C525c using Tapatalk
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Ok, then that's the problem XD
The program is using the ramdisk offset of 0x01000000,
and in the header, there is no way to check the ramdisk_offset and kernel_offset. So I use the standard one.
I did a secure check of ramdisk_address - kernel_address == ramdisk_offset - kernel_offset, to make sure the header is not corrupted.
If you are using one none standard ramdisk_offset
you need to do following change to main.c
1st comment ln46
2nd, change ln48 to base_address = kernel_address - kernel_offset;

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SHM said:
Yea, in mkbootimg.c the standard ramdisk offset is 0x01000000 but my recovery and boot images uses non standard ramdisk offsets. It uses, 0x01608000.
Sent from my C525c using Tapatalk
---------- Post added at 08:40 PM ---------- Previous post was at 08:32 PM ----------
Sent from my C525c using Tapatalk
Click to expand...
Click to collapse
Or I will make some more change to the program, to allow to add some none-standard ramdisk_offset or kernel_offset.

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huuu said:
Or I will make some more change to the program, to allow to add some none-standard ramdisk_offset or kernel_offset.
Click to expand...
Click to collapse
Would recommend doing the same for tags, kernel, and second as well. I came across one image where all offsets were non standard lol. Nice job putting this together though.
Sent from my C525c using Tapatalk

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SHM said:
Would recommend doing the same for tags, kernel, and second as well. I came across one image where all offsets were non standard lol. Nice job putting this together though.
Sent from my C525c using Tapatalk
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Sure, I can do it in the weekend， since I am not able to commit the change to the repository right now XD

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There is an app on the play store called sgit. I use it all the time to clone, commit changes, and push. May be useful to you .
Sent from my C525c using Tapatalk

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SHM said:
There is an app on the play store called sgit. I use it all the time to clone, commit changes, and push. May be useful to you .
Sent from my C525c using Tapatalk
Click to expand...
Click to collapse
Thanks

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SHM said:
There is an app on the play store called sgit. I use it all the time to clone, commit changes, and push. May be useful to you .
Sent from my C525c using Tapatalk
Click to expand...
Click to collapse
Sorry for the delay. I was quit busy those days.
I just finished the code for customized the kernel offset and ramdisk offset parameter, you can try it from my github.
GetImageInfo [--kernel_offset <KernalOffset>] [--ramdisk_offset <RamdiskOffset>] <filename>