Problem of LinuxBoot Implementation on QEMU-ARM64 about linuxboot HOT 2 OPEN

Just for the record, what kernel version is your image and which version of Ubuntu and Ubuntu's kernel?

Sometimes when you don't see any prints, it's because the kernel doesn't know where to find the serial device (a result of not being able to get the ACPI tables). For debugging, you can hard-code the location of the serial device into the kernel command line with:

earlycon=pl011,0x<addr>

Where is something you can extract from qemu with:

qemu-system-aarch64 -machine virt -cpu cortex-a57 -machine dumpdtb=dtb.dtb
fdtdump dtb.dtb

Additionally, I'm curious if this path works:

UEFI(ACPI) ------> Kernel+U-root (Image) ---kexec---> Kernel+U-root (Image)

I am of course curious why a vanilla Linux kernel can't generate the uefi-secure-boot node and whether Ubuntu has some special patches.

from linuxboot.

I used the linux-5.4 for the Linuxboot, and the version of Ubuntu is also linux-5.4.
As for the problem that I couldn't see any print, I ended up finding (with GDB) it's because the kernel gets panic before the initialization of console. The detail of this process you can find here.

UEFI(ACPI) ------> Kernel+U-root (Image) ---kexec---> Kernel+U-root (Image)
For this path, I actually made a virtual disk to store the Image file, which contains the linux-5.4 and u-root.
So at first the Linuxboot firmware(contains the UEFI and the Image file) could run the kernel in the firmware, and then I could mount the virtual disk to find the Image file, thus I could run the kernel in the virtual disk by kexec.

For the 3rd question, I have to say, Ubuntu indeed has some special patches. :)

from linuxboot.