[PATCH 2/3] kexec: Add DTB carryover support on x86

[Brian Mak <makb@juniper.net>]

Add support for forcing the carryover of the current boot's device tree
blob on x86. This is enabled via the --force-dtb flag.

Signed-off-by: Brian Mak <makb@juniper.net>
---
 kexec/kexec-syscall.h | 1 +
 kexec/kexec.c         | 5 +++++
 kexec/kexec.h         | 4 +++-
 3 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/kexec/kexec-syscall.h b/kexec/kexec-syscall.h
index 77e6b81..d66bd82 100644
--- a/kexec/kexec-syscall.h
+++ b/kexec/kexec-syscall.h
@@ -129,6 +129,7 @@ static inline long kexec_file_load(int kernel_fd, int initrd_fd,
 #define KEXEC_FILE_NO_INITRAMFS	0x00000004
 #define KEXEC_FILE_DEBUG	0x00000008
 #define KEXEC_FILE_NO_CMA	0x00000010
+#define KEXEC_FILE_FORCE_DTB	0x00000020
 
 /* These values match the ELF architecture values. 
  * Unless there is a good reason that should continue to be the case.
diff --git a/kexec/kexec.c b/kexec/kexec.c
index ccdf4cd..acf9699 100644
--- a/kexec/kexec.c
+++ b/kexec/kexec.c
@@ -1103,6 +1103,8 @@ void usage(void)
 	       "                      hot add/remove events, avoiding the need to reload\n"
 	       "                      kdump kernel on online/offline events.\n"
 	       " --no-cma             Don't use CMA for placing kexec payloads.\n"
+	       " --force-dtb          Carry over the current boot's device tree blob (x86\n"
+	       "                      only, this is forced on ARM64 and PPC).\n"
 	       " -d, --debug          Enable debugging to help spot a failure.\n"
 	       " -S, --status         Return 1 if the type (by default crash) is loaded,\n"
 	       "                      0 if not.\n"
@@ -1679,6 +1681,9 @@ int main(int argc, char *argv[])
 		case OPT_NO_CMA:
 			kexec_file_flags |= KEXEC_FILE_NO_CMA;
 			break;
+		case OPT_FORCE_DTB:
+			kexec_file_flags |= KEXEC_FILE_FORCE_DTB;
+			break;
 		default:
 			break;
 		}
diff --git a/kexec/kexec.h b/kexec/kexec.h
index a1edc1e..1489ec3 100644
--- a/kexec/kexec.h
+++ b/kexec/kexec.h
@@ -236,7 +236,8 @@ extern int file_types;
 #define OPT_EXEC_LIVE_UPDATE	264
 #define OPT_HOTPLUG		265
 #define OPT_NO_CMA		266
-#define OPT_MAX		267
+#define OPT_FORCE_DTB		267
+#define OPT_MAX		268
 #define KEXEC_OPTIONS \
 	{ "help",		0, 0, OPT_HELP }, \
 	{ "version",		0, 0, OPT_VERSION }, \
@@ -265,6 +266,7 @@ extern int file_types;
 	{ "print-ckr-size",     0, 0, OPT_PRINT_CKR_SIZE }, \
 	{ "hotplug",		0, 0, OPT_HOTPLUG }, \
 	{ "no-cma",		0, 0, OPT_NO_CMA }, \
+	{ "force-dtb",		0, 0, OPT_FORCE_DTB }, \
 
 #define KEXEC_OPT_STR "h?vdfixyluet:pscaS"
 
-- 
2.34.1