riscv64  cannot use the mret instruction to jump to the address corresponding to s mode
Description of problem:
I use coreboot to boot my linux kernel.The kernel is copied at 0x82200000,I set reg mepc 0x82200000,and set reg mstatus a00000800.
and I use "mret" instruction so that qemu can jump to 0x82200000 and enter S mode.But some errors happened.
It shows:
[DEBUG]  Exception:          Instruction access fault
[DEBUG]  Hart ID:            0
[DEBUG]  Previous mode:      machine
[DEBUG]  Bad instruction pc: 0x8103f7c0
[DEBUG]  Bad address:        0x00000000
[DEBUG]  Stored ra:          0x8103f7b8
[DEBUG]  Stored sp:          0x82032f08
Bad instruction pc: 0x8103f7c0 in my elf file instruction is "mret".
So I can not jump to my kernel's load address.
I think when I use -bios option,my qemu should in M mode.How could I can jump to my mepc address?
Steps to reproduce:
1.download qemu
2.download coreboot
Additional information:
When I enter qemu with -bios option,I find that the reg mstatus is 0xa0000000.