[systemd-devel] [PATCH] shutdown: avoid calling `kexec` binary unnessecarily

[Shawn Landden]

Still use helper when Xen Dom0, to avoid duplicating some hairy code.
So we don't have any logic to load kexec kernels?
---
 TODO                |  3 ---
 src/core/shutdown.c | 33 ++++++++++++++++++++-------------
 2 files changed, 20 insertions(+), 16 deletions(-)

diff --git a/TODO b/TODO
index 883b994..68b0af6 100644
--- a/TODO
+++ b/TODO
@@ -85,9 +85,6 @@ Features:
 * maybe introduce WantsMountsFor=? Usecase:
   http://lists.freedesktop.org/archives/systemd-devel/2015-January/027729.html
 
-* rework kexec logic to use new kexec_file_load() syscall, so that we
-  don't have to call kexec tool anymore.
-
 * The udev blkid built-in should expose a property that reflects
   whether media was sensed in USB CF/SD card readers. This should then
   be used to control SYSTEMD_READY=1/0 so that USB card readers aren't
diff --git a/src/core/shutdown.c b/src/core/shutdown.c
index 71f001a..c64c05d 100644
--- a/src/core/shutdown.c
+++ b/src/core/shutdown.c
@@ -350,26 +350,33 @@ int main(int argc, char *argv[]) {
         case LINUX_REBOOT_CMD_KEXEC:
 
                 if (!in_container) {
-                        /* We cheat and exec kexec to avoid doing all its work */
-                        pid_t pid;
+                        _cleanup_free_ char *param = NULL;
 
                         log_info("Rebooting with kexec.");
 
-                        pid = fork();
-                        if (pid < 0)
-                                log_error_errno(errno, "Failed to fork: %m");
-                        else if (pid == 0) {
+                        /* kexec-tools has a bunch of special code to make Xen Dom0 work,
+                         * otherwise it is only doing stuff we have already done */
+                        if (access("/proc/xen", F_OK) == 0) {
+                                pid_t pid;
+
+                                pid = fork();
+                                if (pid < 0)
+                                        log_error_errno(errno, "Failed to fork: %m");
+                                else if (pid == 0) {
+
+                                        const char * const args[] = {
+                                                KEXEC, "-e", NULL
+                                        };
 
-                                const char * const args[] = {
-                                        KEXEC, "-e", NULL
-                                };
+                                        /* Child */
 
-                                /* Child */
+                                        execv(args[0], (char * const *) args);
+                                        _exit(EXIT_FAILURE);
+                                } else
+                                        wait_for_terminate_and_warn("kexec", pid, true);
 
-                                execv(args[0], (char * const *) args);
-                                _exit(EXIT_FAILURE);
                         } else
-                                wait_for_terminate_and_warn("kexec", pid, true);
+                                reboot(cmd);
                 }
 
                 cmd = RB_AUTOBOOT;
-- 
2.2.1.209.g41e5f3a