[PATCH v6 0/1] Add support for grub-emu to kexec Linux menu entries

[Robbie Harwood]

Address feedback from Daniel's third review (interdiff attached).

Be well,
--Robbie

Raymund Will (1):
  Add support for grub-emu to kexec Linux menu entries

 docs/grub.texi               |  30 ++++--
 grub-core/Makefile.am        |   1 +
 grub-core/Makefile.core.def  |   2 +-
 grub-core/kern/emu/main.c    |   4 +
 grub-core/kern/emu/misc.c    |  18 +++-
 grub-core/loader/emu/linux.c | 178 +++++++++++++++++++++++++++++++++++
 include/grub/emu/exec.h      |   4 +-
 include/grub/emu/hostfile.h  |   3 +-
 include/grub/emu/misc.h      |   3 +
 9 files changed, 231 insertions(+), 12 deletions(-)
 create mode 100644 grub-core/loader/emu/linux.c

Interdiff against v5:
diff --git a/docs/grub.texi b/docs/grub.texi
index 1463e62e6b..1663a076c0 100644
--- a/docs/grub.texi
+++ b/docs/grub.texi
@@ -1,4 +1,4 @@
-i\input texinfo
+\input texinfo
 @c -*-texinfo-*-
 @c %**start of header
 @setfilename grub.info
@@ -962,11 +962,15 @@ information.
 @node Kexec
 @subsection Kexec with grub2-emu
 
-grub2 can be run in userspace by invoking the grub2-emu tool.  It will
+GRUB can be run in userspace by invoking the grub2-emu tool.  It will
 read all configuration scripts as if booting directly (see @xref{Loading
 an operating system directly}).  With the @code{--kexec} flag, and
 kexec(8) support from the operating system, the @command{linux} command
-will directly boot the target image.
+will directly boot the target image.  For systems that lack working
+systemctl(1) support for kexec, passing the @code{--kexec} flag twice
+will fallback to invoking kexec(8) directly; note however that this
+fallback may be unsafe outside read-only environments, as it does not
+invoke shutdown machinery.
 
 
 @node Chain-loading
diff --git a/grub-core/loader/emu/linux.c b/grub-core/loader/emu/linux.c
index f232f195b3..0cf378a376 100644
--- a/grub-core/loader/emu/linux.c
+++ b/grub-core/loader/emu/linux.c
@@ -38,8 +38,7 @@ grub_linux_boot (void)
 {
   grub_err_t rc = GRUB_ERR_NONE;
   char *initrd_param;
-  const char *kexec[] = {"kexec", "-la", kernel_path, boot_cmdline, NULL,
-         NULL};
+  const char *kexec[] = {"kexec", "-la", kernel_path, boot_cmdline, NULL, 
NULL};
   const char *systemctl[] = {"systemctl", "kexec", NULL};
   int kexecute = grub_util_get_kexecute ();
 
@@ -59,7 +58,7 @@ grub_linux_boot (void)
   if (kexecute)
     rc = grub_util_exec (kexec);
 
-  grub_free(initrd_param);
+  grub_free (initrd_param);
 
   if (rc != GRUB_ERR_NONE)
     {
@@ -82,13 +81,12 @@ grub_linux_boot (void)
    * WARNING: forcible reset should only be used in read-only environments.
    * grub-emu cannot check for these - users beware.
    */
-  grub_dprintf ("linux", "Performing 'kexec -e -x'");
-  kexec[1] = "-e";
-  kexec[2] = "-x";
-  kexec[3] = NULL;
+  grub_dprintf ("linux", "Performing 'kexec -ex'");
+  kexec[1] = "-ex";
+  kexec[2] = NULL;
   rc = grub_util_exec (kexec);
-  if ( rc != GRUB_ERR_NONE )
-    grub_fatal (N_("error trying to directly perform 'kexec -e': %d"), rc);
+  if (rc != GRUB_ERR_NONE)
+    grub_fatal (N_("error trying to directly perform 'kexec -ex': %d"), rc);
 
   return rc;
 }
@@ -129,7 +127,7 @@ grub_cmd_linux (grub_command_t cmd __attribute__ 
((unused)), int argc,
   if (argc > 1)
     {
       boot_cmdline = grub_xasprintf ("--command-line=%s", argv[1]);
-      for ( i = 2; i < argc; i++ )
+      for (i = 2; i < argc; i++)
         {
           tempstr = grub_xasprintf ("%s %s", boot_cmdline, argv[i]);
           grub_free (boot_cmdline);
@@ -154,7 +152,7 @@ grub_cmd_initrd (grub_command_t cmd __attribute__ 
((unused)), int argc,
                       N_("Cannot find initrd file %s"), argv[0]);
 
   grub_free (initrd_path);
-  initrd_path = grub_xasprintf("%s", argv[0]);
+  initrd_path = grub_xasprintf ("%s", argv[0]);
 
   /* We are done - mark ourselves as on longer in use. */
   grub_dl_unref (my_mod);
@@ -171,9 +169,6 @@ GRUB_MOD_INIT (linux)
   cmd_initrd = grub_register_command ("initrd", grub_cmd_initrd, 0,
                                      N_("Load initrd."));
   my_mod = mod;
-  kernel_path = NULL;
-  initrd_path = NULL;
-  boot_cmdline = NULL;
 }
 
 GRUB_MOD_FINI (linux)
-- 
2.35.1