What is the kernel die message What is the kernel die message 0

error

(XEN) *** LOADING DOMAIN 0 ***
(XEN) Loading d0 kernel from boot module @ 00000000b936c000
(XEN) Allocating 1:1 mappings totalling 512MB for dom0:
(XEN) BANK[0] 0x000000c0000000-0x000000e0000000 (512MB)
(XEN) Grant table range: 0x000000b921c000-0x000000b925c000
(XEN) Allocating PPI 16 for event channel interrupt
(XEN) Loading zImage from 00000000b936c000 to 00000000c0080000-00000000c1187200
(XEN) Loading d0 DTB to 0x00000000c8000000-0x00000000c800a813
...
[    0.000000] Booting Linux on physical CPU 0x0
[    0.000000] Boot CPU: AArch64 Processor [410fd034]
[    0.000000] Machine model: HiKey960
[    0.000000] Xen 4.13 support found
[    0.000000] Kernel command line: console=tty0 console=hvc0 root=/dev/sdd10 rw efi=noruntime
[    0.000000] PID hash table entries: 2048 (order: 2, 16384 bytes)
[    0.000000] Memory: 456156K/525312K available (10364K kernel code, 1180K rwdata, 4664K rodata, 1152K init, 405K bss, 52772K reserved, 16384K cma-reserved)
...
[    7.067414] --CJ  enter prepare_namespace: root_delay=0
[    7.294633] ufshcd-hi3660 ff3b0000.ufs: ufshcd_query_flag: Sending flag query for idn 3 failed, err = -11
[    7.683146] xhci-hcd xhci-hcd.0.auto: USB bus 2 deregistered
[    7.688722] xhci-hcd xhci-hcd.0.auto: remove, state 1
...
[   14.998578] ufshcd-hi3660 ff3b0000.ufs: ufshcd_init_icc_levels: Failed reading power descriptor.len = 98 ret = -11
[   36.480083] ufshcd-hi3660 ff3b0000.ufs: ufshcd_print_pwr_info:[RX, TX]: gear=[1, 1], lane[1, 1], pwr[SLOWAUTO_MODE, SLOWAUTO_MODE], rate = 0
[   36.493073] ufshcd-hi3660 ff3b0000.ufs: UPIU[0] - issue time 14654573 us
...
[   36.755689] ufshcd-hi3660 ff3b0000.ufs: ufshcd_print_pwr_info:[RX, TX]: gear=[3, 3], lane[2, 2], pwr[FAST MODE, FAST MODE], rate = 2
[   36.767798] --CJ in mount_root: entering mount_block_root(/dev/root, 0x8000)
[   36.774793] --CJ mount_block_root: name=/dev/root, fs_names = 
[   36.862337] -CJ do_mount_root (/dev/root, ext3)
 
[   36.866925] VFS: Cannot open root device "sdd10" or unknown-block(0,0): error -6
[   36.874332] Please append a correct "root=" boot option; here are the available partitions:
[   36.882734] --CJ printk_all_partitions: 
[   36.886730] -- -- CJ loop 1
[   36.889578] -- -- CJ loop 1
[   36.892442] -- -- CJ loop 1
[   36.895304] -- -- CJ loop 1
[   36.898157] -- -- CJ loop 1
[   36.901025] -- -- CJ loop 1
[   36.903889] -- -- CJ loop 1
[   36.906751] -- -- CJ loop 1
[   36.909613] Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)
[   36.930939] Call trace:
[   36.933464] [<ffff000008088be0>] dump_backtrace+0x0/0x370
[   36.938925] [<ffff000008088f64>] show_stack+0x14/0x20
[   36.944037] [<ffff000008a71200>] dump_stack+0x9c/0xbc
[   36.949159] [<ffff0000080c78d8>] panic+0x11c/0x28c
[   36.954011] [<ffff000008f41184>] mount_block_root+0x1bc/0x290
[   36.959817] [<ffff000008f41384>] mount_root+0x12c/0x144
[   36.965107] [<ffff000008f414e4>] prepare_namespace+0x148/0x190
[   36.971005] [<ffff000008f40d8c>] kernel_init_freeable+0x208/0x22c
[   36.977163] [<ffff000008a836e8>] kernel_init+0x10/0x100
[   36.982451] [<ffff000008084b58>] ret_from_fork+0x10/0x18
[   36.987832] SMP: stopping secondary CPUs

init\do_mount.c

void __init prepare_namespace(void)
{
        ROOT_DEV = name_to_dev_t(root_device_name);
        root_device_name += 5; //remove /dev/
	mount_root();
}
 
void __init mount_root(void)
{
		int err = create_dev("/dev/root", ROOT_DEV); (= mknod (/dev/root->ROOT_DEV)
		mount_block_root("/dev/root", root_mountflags/=0x8000/);
}
 
void __init mount_block_root(char *name, int flags) //name shouldn't be sdd10
	for (p = fs_names; *p; p += strlen(p)+1) {
		int err = do_mount_root(name, p, flags, root_mount_data);
                //SYS_MOUNT("/dev/root", "/root","ext3") error = -6
 
		__bdevname(ROOT_DEV, b); //ROOT_DEV=0
		printk("VFS: Cannot open root device \"%s\" or %s: error %d\n",
				root_device_name, b, err);
//VFS: Cannot open root device "sdd10" or unknown-block(0,0): error -6
//root_device_name = sdd10 跟 /dev/root 有什麼關係？
//why ROOT_DEV = 0,0: node created but not mount 
 
		printk("Please append a correct \"root=\" boot option; here are the available partitions:\n");
		printk_all_partitions();//NO OUTPUT
		panic("VFS: Unable to mount root fs on %s", b);
                // VFS: Unable to mount root fs on unknown-block(0,0)
	}
 
}
 
static int __init do_mount_root(char *name, char *fs, int flags, void *data)
{
	struct super_block *s;
	int err = sys_mount(name, "/root", fs, flags, data);
	if (err)
		return err;
 
	sys_chdir("/root");
	s = current->fs->pwd.dentry->d_sb;
	ROOT_DEV = s->s_dev;
	printk(KERN_INFO
	       "VFS: Mounted root (%s filesystem)%s on device %u:%u.\n",
	       s->s_type->name,
	       sb_rdonly(s) ? " readonly" : "",
	       MAJOR(ROOT_DEV), MINOR(ROOT_DEV));
	return 0;
}
 
 
 
dev_t name_to_dev_t(const char *name)
{
	char s[32];
	char *p;
	dev_t res = 0;
	int part;
 
#ifdef CONFIG_BLOCK
	if (strncmp(name, "PARTUUID=", 9) == 0) {
		name += 9;
		res = devt_from_partuuid(name);
		if (!res)
			goto fail;
		goto done;
	}
#endif
 
	if (strncmp(name, "/dev/", 5) != 0) {
		unsigned maj, min, offset;
		char dummy;
 
		if ((sscanf(name, "%u:%u%c", &maj, &min, &dummy) == 2) ||
		    (sscanf(name, "%u:%u:%u:%c", &maj, &min, &offset, &dummy) == 3)) {
			res = MKDEV(maj, min);
			if (maj != MAJOR(res) || min != MINOR(res))
				goto fail;
		} else {
			res = new_decode_dev(simple_strtoul(name, &p, 16));
			if (*p)
				goto fail;
		}
		goto done;
	}
 
	name += 5;
	res = Root_NFS;
	if (strcmp(name, "nfs") == 0)
		goto done;
	res = Root_RAM0;
	if (strcmp(name, "ram") == 0)
		goto done;
 
	if (strlen(name) > 31)
		goto fail;
	strcpy(s, name);
	for (p = s; *p; p++)
		if (*p == '/')
			*p = '!';
printk("--- blk_lookup_edvt(%s)\n", s);
	res = blk_lookup_devt(s, 0);
	if (res)
		goto done;
 
	/*
	 * try non-existent, but valid partition, which may only exist
	 * after revalidating the disk, like partitioned md devices
	 */
	while (p > s && isdigit(p[-1]))
		p--;
	if (p == s || !*p || *p == '0')
		goto fail;
 
	/* try disk name without <part number> */
	part = simple_strtoul(p, NULL, 10);
	*p = '\0';
printk("--CJ 2nd blk_lookup_dvt(%s)\n", s);
	res = blk_lookup_devt(s, part);
	if (res)
		goto done;
 
	/* try disk name without p<part number> */
	if (p < s + 2 || !isdigit(p[-2]) || p[-1] != 'p')
		goto fail;
	p[-1] = '\0';
printk("--CJ 3rd bLk_lookup %s\n", s);
	res = blk_lookup_devt(s, part);
	if (res)
		goto done;
 
fail:
	return 0;
done:
	return res;
}

./block/genhd.c

void __init printk_all_partitions(void)
{
	struct class_dev_iter iter;
	struct device *dev;
printk("--CJ printk_all_partitions: \n");
	class_dev_iter_init(&iter, &block_class, NULL, &disk_type);
	while ((dev = class_dev_iter_next(&iter))) {
		struct gendisk *disk = dev_to_disk(dev);
		struct disk_part_iter piter;
		struct hd_struct *part;
		char name_buf[BDEVNAME_SIZE];
		char devt_buf[BDEVT_SIZE];
printk("-- -- CJ loop 1\n");
		/*
		 * Don't show empty devices or things that have been
		 * suppressed
		 */
		if (get_capacity(disk) == 0 ||
		    (disk->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.
		 */
		disk_part_iter_init(&piter, disk, DISK_PITER_INCL_PART0);
		while ((part = disk_part_iter_next(&piter))) {
			bool is_part0 = part == &disk->part0;
 
			printk("%s%s %10llu %s %s", is_part0 ? "" : "  ",
			       bdevt_str(part_devt(part), devt_buf),
			       (unsigned long long)part_nr_sects_read(part) >> 1
			       , disk_name(disk, part->partno, name_buf),
			       part->info ? part->info->uuid : "");
			if (is_part0) {
				if (dev->parent && dev->parent->driver)
					printk(" driver: %s\n",
					      dev->parent->driver->name);
				else
					printk(" (driver?)\n");
			} else
				printk("\n");
		}
		disk_part_iter_exit(&piter);
	}
	class_dev_iter_exit(&iter);
}