Hi,
We have tried to boot the Ubuntu kernel 5.10 [1] (arm64) with U-Boot 2020.10 on RPi 4B. That includes the source code and build config. The kernel's build config enables not only Broadcom chips, but also many other platforms: Amlogic, MediaTek, Realtek, Rockchip ... by default.
Here is the output from U-Boot:
U-Boot 2020.10 (Jan 26 2021 - 15:28:45 +0800)
DRAM: 3.9 GiB RPI 4 Model B (0xc03111) MMC: mmcnr@7e300000: 1, emmc2@7e340000: 0 Loading Environment from FAT... *** Warning - bad CRC, using default environment
In: serial Out: vidconsole Err: vidconsole Net: eth0: genet@7d580000 Hit any key to stop autoboot: 0 switch to partitions #0, OK mmc0 is current device Scanning mmc 0:2... Found U-Boot script /boot/boot.scr 1847 bytes read in 19 ms (94.7 KiB/s) ## Executing script at 02400000 Load u-Boot environment ... from mmc 0:2 622 bytes read in 24 ms (24.4 KiB/s) Load device tree ... 25693 bytes read in 30 ms (835.9 KiB/s) fdt_addr_r @ 0x02600000 , size= 645d Load kernel and unzip it ... 13013555 bytes read in 574 ms (21.6 MiB/s) Uncompressed size: 38742528 = 0x24F2A00 kernel_addr_r @ 0x00080000 , size= 24f2a00 Load RAM disk ... 54360540 bytes read in 2298 ms (22.6 MiB/s) ramdisk_addr_r @ 0x02700000 , size= 33d79dc Boot ... Moving Image from 0x80000 to 0x200000, end=2820000 ERROR: RD image overlaps OS image (OS=0x200000..0x2820000) SCRIPT FAILED: continuing... Card did not respond to voltage select! genet@7d580000 Waiting for PHY auto negotiation to complete........
It shows error: "RD image overlaps OS image (OS=0x200000..0x2820000)"
So, I calculated the memory address and space:
0x200000 (kernel start address) + 0x24F2A00 (kernel size) = 0x26F2A00 < 2820000 (kernel end), but > 0x2700000 (ramdisk start address) & > 0x2600000 (FDT start address)
The kernel image size 0x24F2A00 bytes is too fat to sit in the memory space prepared by U-Boot and overlaps ramdisk and FDT's memory spaces. It is more than 36.9MB, which is over 36MB mentioned in U-Boot's comment [2].
We understand this can be fixed by a workaround like tuning/reducing the kernel's build config. However, is it possible to have another way to resolve this problem?
[1] https://kernel.ubuntu.com/git/ubuntu/unstable.git/tree/?h=Ubuntu-5.10-5.10.0... [2] https://github.com/u-boot/u-boot/blob/v2021.01/include/configs/rpi.h#L140
Jain-Hong Pan