-1

I'm performance testing an MMC to failure and would like to use tools like smartmon-tools and mmc-utils to check drive health as I write data. I'm stuck since I can't find the device path of my MMC. In mount and lsblk I see it at /dev/mmcblk0 but my tools can't seem to open it.

root@host:/# lsblk -p
NAME              MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
/dev/mmcblk0      179:0    0 29.1G  0 disk 
├─/dev/mmcblk0p1  179:1    0    4K  0 part 
├─/dev/mmcblk0p2  179:2    0    1M  0 part 
├─/dev/mmcblk0p3  179:3    0  896K  0 part 
├─/dev/mmcblk0p4  179:4    0    1M  0 part 
├─/dev/mmcblk0p5  179:5    0   20M  0 part 
├─/dev/mmcblk0p6  179:6    0   20M  0 part 
├─/dev/mmcblk0p7  179:7    0   20M  0 part 
├─/dev/mmcblk0p8  179:8    0  1.5G  0 part /mnt/hostfs/usr/local/bin
├─/dev/mmcblk0p9  179:9    0  1.5G  0 part 
├─/dev/mmcblk0p10 179:10   0   50M  0 part /etc/network
├─/dev/mmcblk0p11 179:11   0   50M  0 part 
├─/dev/mmcblk0p12 179:12   0  9.8G  0 part /mnt/data
└─/dev/mmcblk0p13 179:13   0 16.3G  0 part /
/dev/mmcblk0boot0 179:32   0    4M  1 disk 
/dev/mmcblk0boot1 179:64   0    4M  1 disk 
root@host:/# mmc extcsd read /dev/mmcblk0
open: No such file or directory
root@acu14216:/# ls -lA /dev/mmcblk0
ls: cannot access '/dev/mmcblk0': No such file or directory

Results of findmnt:

TARGET                                SOURCE                                                            FSTYPE    OPTIONS
/                                     /dev/mmcblk0p13                                                   ext4      rw,relatime,data=ordered
├─/tmp                                tmpfs                                                             tmpfs     rw,nosuid,nodev
├─/sys                                sysfs                                                             sysfs     ro,nosuid,nodev,noexec,relatime
│ ├─/sys/fs/cgroup                    tmpfs                                                             tmpfs     ro,nosuid,nodev,noexec,mode=755
│ │ ├─/sys/fs/cgroup/hugetlb          cgroup                                                            cgroup    ro,nosuid,nodev,noexec,relatime,hugetlb
│ │ ├─/sys/fs/cgroup/cpu              cgroup                                                            cgroup    ro,nosuid,nodev,noexec,relatime,cpu
│ │ ├─/sys/fs/cgroup/unified          cgroup                                                            cgroup2   rw,nosuid,nodev,noexec,relatime,nsdelegate
│ │ └─/sys/fs/cgroup/systemd          cgroup                                                            cgroup    rw,nosuid,nodev,noexec,relatime,xattr,name=systemd
│ ├─/sys/class/gpio                   sysfs[/class/gpio]                                                sysfs     rw,nosuid,nodev,noexec,relatime
│ └─/sys/devices/platform             sysfs[/devices/platform]                                          sysfs     rw,nosuid,nodev,noexec,relatime
├─/dev                                tmpfs                                                             tmpfs     rw,nosuid,mode=755
│ ├─/dev/hugepages                    hugetlbfs                                                         hugetlbfs rw,relatime,pagesize=2M
│ ├─/dev/shm                          tmpfs                                                             tmpfs     rw,nosuid,nodev
│ ├─/dev/pts                          devpts                                                            devpts    rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=666
│ ├─/dev/console                      devpts[/0]                                                        devpts    rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000
│ ├─/dev/iav                          devtmpfs[/iav]                                                    devtmpfs  rw,relatime,size=214184k,nr_inodes=53546,mode=755
│ ├─/dev/null                         devtmpfs[/null]                                                   devtmpfs  rw,relatime,size=214184k,nr_inodes=53546,mode=755
│ ├─/dev/snd                          devtmpfs[/snd]                                                    devtmpfs  rw,relatime,size=214184k,nr_inodes=53546,mode=755
│ ├─/dev/ttyS1                        devtmpfs[/ttyS1]                                                  devtmpfs  rw,relatime,size=214184k,nr_inodes=53546,mode=755
│ └─/dev/mqueue                       mqueue                                                            mqueue    rw,nosuid,nodev,noexec,relatime
├─/run                                tmpfs                                                             tmpfs     rw,nosuid,nodev,mode=755
│ ├─/run/lock                         tmpfs                                                             tmpfs     rw,nosuid,nodev,noexec,relatime,size=5120k
│ ├─/run/systemd/nspawn/incoming      tmpfs[/systemd/nspawn/propagate/ambian]                           tmpfs     ro,mode=755
│ ├─/run/openvpn                      tmpfs[/openvpn]                                                   tmpfs     rw,nosuid,nodev,mode=755
│ └─/run/user/1000                    tmpfs                                                             tmpfs     rw,nosuid,nodev,relatime,size=205068k,mode=700,uid=1000,gid=1003
├─/etc/network                        /dev/mmcblk0p10[/etc/network]                                     ext4      rw,relatime,data=ordered
├─/mnt/data                           /dev/localstoragep1                                               ext4      rw,relatime,data=ordered
├─/mnt/hostfs/usr/bin                 /dev/mmcblk0p8[/usr/bin]                                          ext4      rw,relatime,errors=remount-ro,data=ordered
├─/mnt/hostfs/usr/local/bin           /dev/mmcblk0p8[/usr/local/bin]                                    ext4      rw,relatime,errors=remount-ro,data=ordered
└─/proc                               proc                                                              proc      rw,nosuid,nodev,noexec,relatime
  ├─/proc/sys/kernel/random/boot_id   tmpfs[/.#proc-sys-kernel-random-boot-id80967b114d82f811//deleted] tmpfs     rw,nosuid,nodev,mode=755
  ├─/proc/kmsg                        tmpfs[/.#proc-kmsgeb9dd69debe4bd57//deleted]                      tmpfs     rw,nosuid,nodev,mode=755
  ├─/proc/sys                         proc[/sys]                                                        proc      ro,nosuid,nodev,noexec,relatime
  │ └─/proc/sys/kernel/random/boot_id tmpfs[/.#proc-sys-kernel-random-boot-id80967b114d82f811//deleted] tmpfs     ro,nosuid,nodev,noexec,mode=755
  ├─/proc/kallsyms                    tmpfs[/systemd/inaccessible/reg]                                  tmpfs     ro,nosuid,nodev,noexec,mode=755
  ├─/proc/keys                        tmpfs[/systemd/inaccessible/reg]                                  tmpfs     ro,nosuid,nodev,noexec,mode=755
  ├─/proc/timer_list                  tmpfs[/systemd/inaccessible/reg]                                  tmpfs     ro,nosuid,nodev,noexec,mode=755
  ├─/proc/asound                      proc[/asound]                                                     proc      ro,nosuid,nodev,noexec,relatime
  ├─/proc/bus                         proc[/bus]                                                        proc      ro,nosuid,nodev,noexec,relatime
  ├─/proc/fs                          proc[/fs]                                                         proc      ro,nosuid,nodev,noexec,relatime
  └─/proc/irq                         proc[/irq]                                                        proc      ro,nosuid,nodev,noexec,relatime

Where is my MMC?

Scott S
  • 101

1 Answers1

1

You're working in a container, so you do not have access to the real /dev filesystem – the only devices available to you are those that were created or linked by the container manager.

(As you can see from 'findmnt', /dev is a "tmpfs" – not a "devtmpfs" – so its contents are not managed by the kernel; in this case systemd-nspawn has provided a few standard device nodes, and bound a few specific ones from the host's /dev.)

The 'lsblk' tool can see the devices through the /sys filesystem (which the container provides a read-only but real version of), but the names it shows are computed from information available through /sys, not from directly looking in /dev.

grawity
  • 501,077