[coreboot-gerrit] New patch to review for coreboot: b086132 X86: make the SIPI num_starts a config variable

[Ronald G. Minnich (rminnich@gmail.com)]

Ronald G. Minnich (rminnich at gmail.com) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/3796

-gerrit

commit b086132df15971624b80e10abeabc98fc5d58677
Author: Ronald G. Minnich <rminnich at gmail.com>
Date:   Mon Jul 22 20:17:18 2013 +0200

    X86: make the SIPI num_starts a config variable
    
    The code to figure out how to set num_starts was
    starting to get kludgy. It's a constant for a given
    CPU; constants should be constant; make it a config variable.
    
    This change includes an example of how to override it.
    Build but not boot tested; drivers welcome.
    
    Change-Id: Iddd906a707bb16251615c7b42f2bfb5a044379b4
    Signed-off-by: Ronald G. Minnich <rminnich at gmail.com>
---
 src/arch/x86/Kconfig               |  9 +++++++++
 src/cpu/amd/model_10xxx/Kconfig    |  4 ++++
 src/cpu/x86/lapic/lapic_cpu_init.c | 12 +++---------
 3 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/src/arch/x86/Kconfig b/src/arch/x86/Kconfig
index 581a048..0a21fcc 100644
--- a/src/arch/x86/Kconfig
+++ b/src/arch/x86/Kconfig
@@ -48,6 +48,15 @@ config MAX_REBOOT_CNT
 	int
 	default 3
 
+# This is something you almost certainly don't want to mess with.
+# How many SIPIs do we send when starting up APs and cores?
+# The answer in 2000 or so was '2'. Nowadays, on many systems,
+# it is 1. Set a safe default here, and you can override it
+# on reasonable platforms.
+config NUM_IPI_STARTS
+	int
+	default 2
+
 # We had to rename the choice options under arch/ because otherwise
 # the options would conflict between different architectures despite
 # the if ARCH_xxx guarding the arch/xxx/Kconfig sourcing.
diff --git a/src/cpu/amd/model_10xxx/Kconfig b/src/cpu/amd/model_10xxx/Kconfig
index e4367f9..99358e0 100644
--- a/src/cpu/amd/model_10xxx/Kconfig
+++ b/src/cpu/amd/model_10xxx/Kconfig
@@ -8,6 +8,10 @@ config CPU_AMD_MODEL_10XXX
 
 if CPU_AMD_MODEL_10XXX
 
+config NUM_IPI_STARTS
+	int
+	default 1
+
 config CPU_ADDR_BITS
 	int
 	default 48
diff --git a/src/cpu/x86/lapic/lapic_cpu_init.c b/src/cpu/x86/lapic/lapic_cpu_init.c
index a3bab46..cd09280 100644
--- a/src/cpu/x86/lapic/lapic_cpu_init.c
+++ b/src/cpu/x86/lapic/lapic_cpu_init.c
@@ -101,7 +101,7 @@ static int lapic_start_cpu(unsigned long apicid)
 {
 	int timeout;
 	unsigned long send_status, accept_status;
-	int j, num_starts, maxlvt;
+	int j, maxlvt;
 
 	/*
 	 * Starting actual IPI sequence...
@@ -167,20 +167,14 @@ static int lapic_start_cpu(unsigned long apicid)
 		return 0;
 	}
 
-#if !CONFIG_CPU_AMD_MODEL_10XXX
-	num_starts = 2;
-#else
-	num_starts = 1;
-#endif
-
 	/*
 	 * Run STARTUP IPI loop.
 	 */
-	printk(BIOS_SPEW, "#startup loops: %d.\n", num_starts);
+	printk(BIOS_SPEW, "#startup loops: %d.\n", CONFIG_NUM_IPI_STARTS);
 
 	maxlvt = 4;
 
-	for (j = 1; j <= num_starts; j++) {
+	for (j = 1; j <= CONFIG_NUM_IPI_STARTS; j++) {
 		printk(BIOS_SPEW, "Sending STARTUP #%d to %lu.\n", j, apicid);
 		lapic_read_around(LAPIC_SPIV);
 		lapic_write(LAPIC_ESR, 0);