Add NV flag to default boot legacy OS

In developer mode, this option will make the system try to boot into
a legacy OS first after the 30 second timeout. This removes the need to
press a key during boot to try legacy mode and the need to remove the
write protect screw to boot legacy as default.

BUG=chromium:310697
BRANCH=none
TEST=make runtests

Change-Id: I9a9f64c14ad015e21d08eec36e8fc187189cd2f2
Signed-off-by: Mary Ruthven <mruthven@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/304077
Reviewed-by: Randall Spangler <rspangler@chromium.org>

1 files changed, 15 insertions, 0 deletions

diff --git a/host/lib/crossystem.c b/host/lib/crossystem.c
index 3080344d..e2066cee 100644
--- a/host/lib/crossystem.c
+++ b/host/lib/crossystem.c
@@ -61,6 +61,7 @@ typedef enum VbBuildOption {
 } VbBuildOption;
 
 static const char *fw_results[] = {"unknown", "trying", "success", "failure"};
+static const char *default_boot[] = {"disk", "usb", "legacy"};
 
 /* Masks for kern_nv usage by kernel. */
 #define KERN_NV_FWUPDATE_TRIES_MASK 0x0000000F
@@ -586,6 +587,12 @@ const char* VbGetSystemPropertyString(const char* name, char* dest,
       return fw_results[v];
     else
       return "unknown";
+  } else if (!strcasecmp(name,"dev_default_boot")) {
+    int v = VbGetNvStorage(VBNV_DEV_DEFAULT_BOOT);
+    if (v < ARRAY_SIZE(default_boot))
+      return default_boot[v];
+    else
+      return "unknown";
   }
 
   return NULL;
@@ -694,6 +701,14 @@ int VbSetSystemPropertyString(const char* name, const char* value) {
 	return VbSetNvStorage(VBNV_FW_RESULT, i);
     }
     return -1;
+  } else if (!strcasecmp(name, "dev_default_boot")) {
+    int i;
+
+    for (i = 0; i < ARRAY_SIZE(default_boot); i++) {
+      if (!strcasecmp(value, default_boot[i]))
+	return VbSetNvStorage(VBNV_DEV_DEFAULT_BOOT, i);
+    }
+    return -1;
   }
 
   return -1;