[Buildroot] genimage raw partition from multiple files

Michał Łyszczek michal.lyszczek at gmail.com
Wed Aug 2 18:09:01 UTC 2017


W dniu 02.08.2017 o 19:55, Thomas Petazzoni pisze:
> Hello,
> 
> On Wed, 2 Aug 2017 19:25:02 +0200, Michał Łyszczek wrote:
> 
>>> Note that spl is 64k big, and uboot-real must be at offset 256k. Also
>>> this *MUST* be a partition of type 0xa2. Can such thing be done fully in
>>> genimage without post-install script?
>>>   
>>
>> Ok, after messing with source code a little bit a found a way to do what
>> I want. Let's say want to create partition of type 0xA2 for uboot. That
>> partition should contain spl image and full uboot. First create image of
>> that partition - this image will be built from "subpartitions"
>>
>>
>> image uboot.img {
>>         hdimage {
>>                 partition-table = "no"
>>         }
>>
>>         partition spl {
>>                 in-partition-table = "no"
>>                 image = "u-boot-spl.bin.crc"
>>                 offset = 0
>>                 size = 64k
>>         }
>>
>>         partition uboot-full {
>>                 in-partition-table = "no"
>>                 image = "u-boot.img"
>>                 offset = 256k
>>         }
>>
>>         size = 1M
>> }
>>
>> 2 things are very important here, first is "partition-table = "no"" in
>> hdimage, this will tell hdimage not add ANYTHING from itself, so no
>> partition table, no dos magic (55 aa), no mbr at all. All partitions
>> should also have "in-partition-table = "no"" to prevent any additional
>> bytes from genimage.
>>
>> When image is created like that it can be normally added into partition
>> table
>>
>>
>> image sdcard.img {
>>         hdimage {
>>         }
>>
>>         partition uboot-env {
>>                 in-partition-table = "no"
>>                 image = "uboot-env.bin"
>>                 offset = 17408 # 512 * 34 -> just after gpt
>>         }
>>
>>         partition uboot {
>>                 partition-type = 0xa2
>>                 image = "uboot.img"
>>         }
>>
>>  	partition rootfs {
>>                 partition-type = 0x83
>>                 image = "rootfs.ext2"
>>                 size = 500M
>>         }
>> }
>>
>>
>> And that's all, image will generate as expected. This may look like
>> hack, but it is quite clean solution I think. We can avoid any scripts
>> to create such partition for bootloader, and everything is in one place.
> 
> And those two snippets of genimage configuration can be in a single
> genimage.cfg, and both uboot.img and then sdcard.img will be produced
> by a single genimage invocation ? Or do we need a first genimage
> invocation to generate uboot.img, and then a second genimage invocation
> to generate sdcard.img (which requires uboot.img) ?
> 
> Thanks!
> 
> Thomas
> 

Only one invocation of genimage.sh is needed to generate working
sdcard.img. Yes! It's that simple! I attach full genimage.cfg I created
for my port for cyclone5. This genimage.cfg creates fully working
sdcard.img (including uboot.img), and only external script used is
support/script/genimage.sh -c genimage.cfg.

-- 
Best Regards
Łyszczek Michał
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image boot.vfat {
	vfat {
		files = {
			"zImage",
			"socfpga_cyclone5_socrates.dtb"
		}
	}
	size = 8M
}

image uboot.img {
	hdimage {
		partition-table = "no"
	}

	partition spl {
		in-partition-table = "no"
		image = "u-boot-spl.bin.crc"
		offset = 0
		size = 64k
	}

	partition uboot-full {
		in-partition-table = "no"
		image = "u-boot.img"
		offset = 256k
	}

	size = 1M
}

image sdcard.img {
	hdimage {
	}

	partition uboot-env {
		in-partition-table = "no"
		image = "uboot-env.bin"
		offset = 17408 # 512 * 34 -> just after gpt
	}

	partition boot {
		partition-type = 0xc
		bootable = "true"
		image = "boot.vfat"
	}

	partition uboot {
		partition-type = 0xa2
		image = "uboot.img"
	}

	partition rootfs {
		partition-type = 0x83
		image = "rootfs.ext2"
		size = 500M
	}
}
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