diff options
Diffstat (limited to 'src/cpu/x86/early_reset.S')
| -rw-r--r-- | src/cpu/x86/early_reset.S | 45 |
1 files changed, 45 insertions, 0 deletions
diff --git a/src/cpu/x86/early_reset.S b/src/cpu/x86/early_reset.S new file mode 100644 index 0000000000..ec015abe22 --- /dev/null +++ b/src/cpu/x86/early_reset.S @@ -0,0 +1,45 @@ +/* + * This file is part of the coreboot project. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ + +/* + * input %esp: return address (not pointer to return address!) + * clobber the content of eax, ecx, edx + */ + +#include <cpu/x86/mtrr.h> + +.section .text +.global check_mtrr + +check_mtrr: + /* Use the MTRR default type MSR as a proxy for detecting INIT#. + * Reset the system if any known bits are set in that MSR. That is + * an indication of the CPU not being properly reset. */ + +check_for_clean_reset: + movl $MTRR_DEF_TYPE_MSR, %ecx + rdmsr + andl $(MTRR_DEF_TYPE_EN | MTRR_DEF_TYPE_FIX_EN), %eax + cmp $0, %eax + jnz warm_reset + jmp *%esp + /* perform warm reset */ +warm_reset: + movw $0xcf9, %dx + movb $0x06, %al + outb %al, %dx + /* Should not reach this*/ +.Lhlt: + hlt + jmp .Lhlt |