forked from Mirrors/opensbi

When calling '_reset_regs', it'll reset all registers except some specific registers (ra, a0, a1, and a2). Both boot HART and non-boot HARTs will execute the '_start_warm' function. Therefore, when '_reset_regs' is called in '_start_warm', it will reset all registers except some specific registers (ra, a0, a1 and a2) for both boot HART and non-boot HARTs. Signed-off-by: Zhang Runmin <fmrt19zrmin@163.com> Reviewed-by: Anup Patel <anup@brainfault.org>