[PATCH 0/2] Fix installation issues on ppc64le

[PATCH 0/2] Fix installation issues on ppc64le

[Ismael Luceno]

When the /dev/nvram device is unavailable, the installation fails and
leaves the system in an unbootable state.

The patches in this series introduce a handler for the boilerplate code
and make sure nvram is available.

Ismael Luceno (2):
  Add helper to load linux kmods
  Ensure nvram is available and functional on IEEE1275

 grub-core/osdep/unix/platform.c | 42 +++++++++++++++++++++++++++++----
 1 file changed, 38 insertions(+), 4 deletions(-)

-- 
2.37.1

[PATCH 1/2] Add helper to load linux kmods

[Ismael Luceno]

The function checks for already loaded (incl. built-in) modules first at
/sys/module/, then tries to load it.

Abort when unable to load efivarfs/efivars.

Signed-off-by: Ismael Luceno <iluceno@suse.de>
---
 grub-core/osdep/unix/platform.c | 24 ++++++++++++++++++++----
 1 file changed, 20 insertions(+), 4 deletions(-)

diff --git a/grub-core/osdep/unix/platform.c b/grub-core/osdep/unix/platform.c
index de712211cf09..a5bf064b7cf5 100644
--- a/grub-core/osdep/unix/platform.c
+++ b/grub-core/osdep/unix/platform.c
@@ -26,8 +26,25 @@
 #include <grub/emu/exec.h>
 #include <sys/types.h>
 #include <dirent.h>
+#include <stdio.h>
 #include <string.h>
 #include <errno.h>
+#include <unistd.h>
+
+static int
+linux_kmod_load (const char *name)
+{
+#ifdef __linux__
+  char path[64];
+  if (snprintf (path, sizeof(path), "/sys/module/%s", name) >= sizeof(path))
+    grub_util_error (_("module name `%s' too long"), name);
+  if (!access (path, F_OK))
+    return 0;
+  return grub_util_exec ((const char * []){ "modprobe", "-q", name, NULL });
+#else
+  return 0;
+#endif
+}
 
 static char *
 get_ofpathname (const char *dev)
@@ -149,10 +166,9 @@ grub_install_register_efi (grub_device_t efidir_grub_dev,
       grub_util_error (_("%s: not found"), "efibootmgr");
     }
 
-  /* On Linux, we need the efivars kernel modules.  */
-#ifdef __linux__
-  grub_util_exec ((const char * []){ "modprobe", "-q", "efivars", NULL });
-#endif
+  /* On Linux, we need efivarfs (or the legacy efivars).  */
+  linux_kmod_load ("efivars");
+
   /* Delete old entries from the same distributor.  */
   ret = grub_install_remove_efi_entries_by_distributor (efi_distributor);
   if (ret)
-- 
2.37.1

[PATCH 2/2] Ensure nvram is available and functional on IEEE1275

[Ismael Luceno]

Otherwise the installation will fail, and the system will be left in an
unbootable state.

On ppc64le, the boot process shows:

	Welcome to GRUB!

	error: ../../grub-core/kern/dl.c:380:symbol `grub_disk_get_size' not found.
	Entering rescue mode...
	grub rescue>

Signed-off-by: Ismael Luceno <iluceno@suse.de>
---
 grub-core/osdep/unix/platform.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/grub-core/osdep/unix/platform.c b/grub-core/osdep/unix/platform.c
index a5bf064b7cf5..fd23176e58a0 100644
--- a/grub-core/osdep/unix/platform.c
+++ b/grub-core/osdep/unix/platform.c
@@ -192,12 +192,30 @@ grub_install_register_efi (grub_device_t efidir_grub_dev,
   return ret;
 }
 
+static void
+linux_ensure_nvram (void)
+{
+  int fd;
+#ifndef __linux__
+  return 0;
+#endif
+  if (linux_kmod_load("nvram"))
+    grub_util_error (_("%s: kernel module not found"), "nvram");
+  fd = open ("/dev/nvram", O_RDWR);
+  if (fd == -1)
+    grub_util_error ("/dev/nvram: %s", strerror(errno));
+  close (fd);
+}
+
 void
 grub_install_register_ieee1275 (int is_prep, const char *install_device,
 				int partno, const char *relpath)
 {
   char *boot_device;
 
+  /* On Linux, ensure nvram is available and functional.  */
+  linux_ensure_nvram ();
+
   if (grub_util_exec_redirect_null ((const char * []){ "ofpathname", "--version", NULL }))
     {
       /* TRANSLATORS: This message is shown when required executable `%s'
-- 
2.37.1

Re: [PATCH 2/2] Ensure nvram is available and functional on IEEE1275

[Michael Chang]

On Wed, Aug 24, 2022 at 06:03:11PM +0200, Ismael Luceno wrote:
> Otherwise the installation will fail, and the system will be left in an
> unbootable state.
> 
> On ppc64le, the boot process shows:
> 
> 	Welcome to GRUB!
> 
> 	error: ../../grub-core/kern/dl.c:380:symbol `grub_disk_get_size' not found.
> 	Entering rescue mode...
> 	grub rescue>

The symbol looking up failure due to failed grub-install attempt should
not happen in the first place given this commit should bail it out.

  8ddbdc3bc2 grub-install: Add backup and restore

Apparently there's missing grub_set_install_backup_ponr between
successful image embedding and grub_install_register_ieee1275 and we
should fix that as well.

> 
> Signed-off-by: Ismael Luceno <iluceno@suse.de>
> ---
>  grub-core/osdep/unix/platform.c | 18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
> 
> diff --git a/grub-core/osdep/unix/platform.c b/grub-core/osdep/unix/platform.c
> index a5bf064b7cf5..fd23176e58a0 100644
> --- a/grub-core/osdep/unix/platform.c
> +++ b/grub-core/osdep/unix/platform.c
> @@ -192,12 +192,30 @@ grub_install_register_efi (grub_device_t efidir_grub_dev,
>    return ret;
>  }
>  
> +static void
> +linux_ensure_nvram (void)
> +{
> +  int fd;
> +#ifndef __linux__
> +  return 0;
> +#endif
> +  if (linux_kmod_load("nvram"))
> +    grub_util_error (_("%s: kernel module not found"), "nvram");
> +  fd = open ("/dev/nvram", O_RDWR);
> +  if (fd == -1)
> +    grub_util_error ("/dev/nvram: %s", strerror(errno));
> +  close (fd);
> +}
> +

I'm wondering why it is needed. The nvram module should be loaded
on-demand via linux kernel's request_module() and modalias trick whever
/dev/nvram is accessed.

Thanks,
Michael

>  void
>  grub_install_register_ieee1275 (int is_prep, const char *install_device,
>  				int partno, const char *relpath)
>  {
>    char *boot_device;
>  
> +  /* On Linux, ensure nvram is available and functional.  */
> +  linux_ensure_nvram ();
> +
>    if (grub_util_exec_redirect_null ((const char * []){ "ofpathname", "--version", NULL }))
>      {
>        /* TRANSLATORS: This message is shown when required executable `%s'
> -- 
> 2.37.1
> 
> 
> _______________________________________________
> Grub-devel mailing list
> Grub-devel@gnu.org
> https://lists.gnu.org/mailman/listinfo/grub-devel

Re: [PATCH 2/2] Ensure nvram is available and functional on IEEE1275

[Ismael Luceno]

On Thu, 25 Aug 2022 12:24:17 +0800
Michael Chang <mchang@suse.com> wrote:
<...> 
> Apparently there's missing grub_set_install_backup_ponr between
> successful image embedding and grub_install_register_ieee1275 and we
> should fix that as well.

Thanks for the feedback; I've sent v2.

<...>
> > +  if (linux_kmod_load("nvram"))
> > +    grub_util_error (_("%s: kernel module not found"), "nvram");
> > +  fd = open ("/dev/nvram", O_RDWR);
> > +  if (fd == -1)
> > +    grub_util_error ("/dev/nvram: %s", strerror(errno));
<...> 
> I'm wondering why it is needed. The nvram module should be loaded
> on-demand via linux kernel's request_module() and modalias trick
> whever /dev/nvram is accessed.

It was based on another patch that did so but without the extra
checking, I guess both are wrong.

It's enough checking /dev/nvram is operational; it's necessary
to fail early because other commands down the line may get ENODEV if
the module fails to load (e.g. the file may have been removed). I moved
this to an earlier point in grub-install.