[coreboot-gerrit] Patch set updated for coreboot: arch/x86: Add debug spinloop

[Leroy P Leahy (leroy.p.leahy@intel.com)]

Leroy P Leahy (leroy.p.leahy at intel.com) just uploaded a new patch set to gerrit, which you can find at https://review.coreboot.org/15127

-gerrit

commit ee821d94df3e65525448b78246c8588066c26242
Author: Lee Leahy <leroy.p.leahy at intel.com>
Date:   Tue Jun 7 08:45:17 2016 -0700

    arch/x86: Add debug spinloop
    
    Conditionally add a debug spinloop to enable easy connection of JTAG
    debuggers.
    
    TEST=Build and run on Galileo Gen2 with a JTAG debugger.
    
    Change-Id: I7a21f9e6bfb10912d06ce48447c61202553630d0
    Signed-off-by: Lee Leahy <leroy.p.leahy at intel.com>
---
 src/arch/x86/Kconfig          | 7 +++++++
 src/arch/x86/bootblock_crt0.S | 9 +++++++++
 2 files changed, 16 insertions(+)

diff --git a/src/arch/x86/Kconfig b/src/arch/x86/Kconfig
index 753a13e..70434e9 100644
--- a/src/arch/x86/Kconfig
+++ b/src/arch/x86/Kconfig
@@ -117,6 +117,13 @@ config PC80_SYSTEM
 	bool
 	default y if ARCH_X86
 
+config BOOTBLOCK_DEBUG_SPINLOOP
+	bool
+	default n
+	help
+	  Add a spin (JMP .) in bootblock_crt0.S during early bootblock to wait
+	  for a JTAG debugger to break into the execution sequence.
+
 config BOOTBLOCK_MAINBOARD_INIT
 	string
 
diff --git a/src/arch/x86/bootblock_crt0.S b/src/arch/x86/bootblock_crt0.S
index 5d22f0e..56c5516 100644
--- a/src/arch/x86/bootblock_crt0.S
+++ b/src/arch/x86/bootblock_crt0.S
@@ -32,6 +32,15 @@
 #include <cpu/x86/16bit/reset16.inc>
 #include <cpu/x86/32bit/entry32.inc>
 
+#if IS_ENABLED(CONFIG_BOOTBLOCK_DEBUG_SPINLOOP)
+
+	/* Wait for a JTAG debugger to break in and set EBX non-zero */
+	xor	%ebx, %ebx
+
+debug_spinloop:
+	cmp	$0, %ebx
+	jz	debug_spinloop
+#endif
 
 bootblock_protected_mode_entry: