[Firmware Bug]: Kernel image misaligned at boot, please fix your bootloader!

[paulmenzel]

The boot log of #45 shows the error below:

[    0.000000] [Firmware Bug]: Kernel image misaligned at boot, please fix your bootloader!

@chenglin-tsai, do you know, if that is present also Linux 5.6?

[chenglin-tsai]

The boot log of #45 shows the error below:

[    0.000000] [Firmware Bug]: Kernel image misaligned at boot, please fix your bootloader!

@chenglin-tsai, do you know, if that is present also Linux 5.6?

Hi Paul,

Based on the test log on kernel 5.6.16 before. I didn't see such a warning message.

Test log on kernel 5.6.16:
dentOS_tn4810m_check_swp8_fiber_connection_and_all_other_ports_ok_01272020.log

I saw there is a solution for this warning here: raspberrypi/firmware#1415
Not sure whether this is the right solution.

[paulmenzel]

Sorry, I should have checked first. Linux commit dd4bc60765 (arm64: warn on incorrect placement of the kernel by the bootloader) added that warning in Linux 5.8, so it couldn’t have been shown by Linux 5.6.

I saw there is a solution for this warning here: raspberrypi/firmware#1415

Do you mean adding kernel_address=0x200000? Unfortunately, I didn’t find a commit, where it’s visible in what file it’s done. I guess U-Boot?

[chenglin-tsai]

Sorry, I should have checked first. Linux commit dd4bc60765 (arm64: warn on incorrect placement of the kernel by the bootloader) added that warning in Linux 5.8, so it couldn’t have been shown by Linux 5.6.

I saw there is a solution for this warning here: raspberrypi/firmware#1415

Do you mean adding kernel_address=0x200000? Unfortunately, I didn’t find a commit, where it’s visible in what file it’s done. I guess U-Boot?

Good news. We could change the kernel load address to 0x200000 in 'tools/flat-image-tree.py' to solve this issue. But I am not sure whether it will cause other side effects. Wait for confirmed.

        elif arch == 'arm64':
            self.load = "<0x200000>"
            self.entry = "<0x200000>"

src: https://github.com/dentproject/dentOS/blob/main/tools/flat-image-tree.py

Test log:
dentOS_tn48m_fix_arm64_kernel_load_address_to_0x20000_2021_0218.log

2021/02/19 updates:

 In arch/arm64/include/asm/boot.h:
/*
 * arm64 requires the kernel image to placed at a 2 MB aligned base address
 */
#define MIN_KIMG_ALIGN		SZ_2M

In arch/arm64/kernel/setup.c:
if (!efi_enabled(EFI_BOOT) && ((u64)_text % MIN_KIMG_ALIGN) != 0)
    pr_warn(FW_BUG "Kernel image misaligned at boot, please fix your bootloader!");

I think any kernel load address that mod by SZ_2M equals to zero can pass the check.
https://elixir.bootlin.com/linux/v5.10.4/source/arch/arm64/include/asm/boot.h
https://elixir.bootlin.com/linux/v5.10.4/source/arch/arm64/kernel/setup.c