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-rw-r--r--src/cpu/x86/early_reset.S45
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
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+++ b/src/cpu/x86/early_reset.S
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+/*
+ * 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