Linker script for Kernel can be modified to be more compatible.

[FishyFizz]

gcc --version
gcc (Ubuntu 9.4.0-1ubuntu1~20.04.1) 9.4.0

My build of ucore kernel won't start properly and enters a reboot cycle. I compared my build with a working build and found that the GDT Descriptor that's used in pmm_init() is replaced with zero value when memset(edata, 0, end - edata) is performed.

Disassembly shows that the pmm.o has the GDT Descriptor in section .data.rel.local rather than .data.
After linking, this address is put after .data section in Kernel. This means that the edata symbol defining the end of the .data section will appear before the GDT Descriptor.

//linker script producing the issue
.data : {
    *(.data)
}
PROVIDE(edata = .);

Modify the linker script and make all data type section before edata symble will fix the issue and the kernel will run fine.

//modified linker script
.data : {
    *(.data.*)
}
PROVIDE(edata = .);