Hi,

On Apr 1 2007 22:47, Andrew Morton wrote:
>On Sun, 1 Apr 2007 20:15:53 +0200 (MEST) Jan Engelhardt <[EMAIL PROTECTED]> 
>wrote:
>> 
>> Display all possible partitions when the root filesystem is not mounted.
>> This helps to track spell'o's and missing drivers.
>> 
>> +void printk_all_partitions(void)
>
>I made this __init.

Seems reasonable.
I have done some additional cleanups, see patch below.


>It would be nice to include a sample of the resulting output for people
>to review.

Loaded with PXELINUX...

        LABEL l
                KERNEL bzImage
                APPEND root=/dev/foobar

or root=/dev/sdb both produce:

[...]
VFS: Cannot open root device "foobar" or unknown-block(0,0)
Please append a correct "root=" boot option; here are the available partitions:
0800    8388608 sda driver: sd
  0801     192748 sda1
  0802    8193150 sda2
0810    4194304 sdb driver: sd
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)

With root=/dev/sdb, the list of possible filesystems is also displayed
(a patch that was merged a (long)while back).


---

Integrated __init annotation, and deindented the loop by one level.
Replaces original patch.

Signed-off-by: Jan Engelhardt <[EMAIL PROTECTED]>

Index: linux-2.6.21-rc5/block/genhd.c
===================================================================
--- linux-2.6.21-rc5.orig/block/genhd.c
+++ linux-2.6.21-rc5/block/genhd.c
@@ -215,6 +215,59 @@ struct gendisk *get_gendisk(dev_t dev, i
        return  kobj ? to_disk(kobj) : NULL;
 }
 
+/*
+ * printk a full list of all partitions - intended for
+ * places where the root filesystem can't be mounted and thus
+ * to give the victim some idea of what went wrong
+ */
+void __init printk_all_partitions(void)
+{
+       int n;
+       struct gendisk *sgp;
+       mutex_lock(&block_subsys_lock);
+
+       /* For each block device... */
+       list_for_each_entry(sgp, &block_subsys.kset.list, kobj.entry) {
+               char buf[BDEVNAME_SIZE];
+               /*
+                * Don't show empty devices or things that have been surpressed
+                */
+               if (get_capacity(sgp) == 0 ||
+                 (sgp->flags & GENHD_FL_SUPPRESS_PARTITION_INFO))
+                       continue;
+
+               /*
+                * Note, unlike /proc/partitions, I am showing the numbers in
+                * hex - the same format as the root= option takes.
+                */
+               printk("%02x%02x %10llu %s",
+                      sgp->major, sgp->first_minor,
+                      (unsigned long long)get_capacity(sgp) >> 1,
+                      disk_name(sgp, 0, buf));
+               if (sgp->driverfs_dev != NULL &&
+                 sgp->driverfs_dev->driver != NULL)
+                       printk(" driver: %s\n",
+                              sgp->driverfs_dev->driver->name);
+               else
+                       printk(" (driver?)\n");
+
+               /* now show the partitions */
+               for (n = 0; n < sgp->minors - 1; ++n) {
+                       if (sgp->part[n] == NULL)
+                               continue;
+                       if (sgp->part[n]->nr_sects == 0)
+                               continue;
+                       printk("  %02x%02x %10llu %s\n",
+                              sgp->major, n + 1 + sgp->first_minor,
+                              (unsigned long long)sgp->part[n]->nr_sects >> 1,
+                              disk_name(sgp, n + 1, buf));
+               } /* partition subloop */
+       } /* Block device loop */
+
+       mutex_unlock(&block_subsys_lock);
+       return;
+}
+
 #ifdef CONFIG_PROC_FS
 /* iterator */
 static void *part_start(struct seq_file *part, loff_t *pos)
Index: linux-2.6.21-rc5/include/linux/genhd.h
===================================================================
--- linux-2.6.21-rc5.orig/include/linux/genhd.h
+++ linux-2.6.21-rc5/include/linux/genhd.h
@@ -413,6 +413,7 @@ char *disk_name (struct gendisk *hd, int
 extern int rescan_partitions(struct gendisk *disk, struct block_device *bdev);
 extern void add_partition(struct gendisk *, int, sector_t, sector_t, int);
 extern void delete_partition(struct gendisk *, int);
+extern void printk_all_partitions(void);
 
 extern struct gendisk *alloc_disk_node(int minors, int node_id);
 extern struct gendisk *alloc_disk(int minors);
Index: linux-2.6.21-rc5/init/do_mounts.c
===================================================================
--- linux-2.6.21-rc5.orig/init/do_mounts.c
+++ linux-2.6.21-rc5/init/do_mounts.c
@@ -7,6 +7,7 @@
 #include <linux/root_dev.h>
 #include <linux/security.h>
 #include <linux/delay.h>
+#include <linux/genhd.h>
 #include <linux/mount.h>
 #include <linux/device.h>
 
@@ -307,17 +308,21 @@ retry:
                /*
                 * Allow the user to distinguish between failed sys_open
                 * and bad superblock on root device.
+                * and give them a list of the available devices
                 */
 #ifdef CONFIG_BLOCK
                __bdevname(ROOT_DEV, b);
 #endif
                printk("VFS: Cannot open root device \"%s\" or %s\n",
                                root_device_name, b);
-               printk("Please append a correct \"root=\" boot option\n");
+               printk("Please append a correct \"root=\" boot option; here are 
the available partitions:\n");
 
+               printk_all_partitions();
                panic("VFS: Unable to mount root fs on %s", b);
        }
 
+       printk("List of all partitions:\n");
+       printk_all_partitions();
        printk("No filesystem could mount root, tried: ");
        for (p = fs_names; *p; p += strlen(p)+1)
                printk(" %s", p);
#<EOF>
-
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