概要
dmesg はカーネルが出力したメッセージを表示するコマンド。
SDカードのマウント等に関係したメッセージを確認することで、例えばマウントでエラーが起きていないかなど確認できるっぽい。
他にもデバイスファイル名の確認にもなるかも？
例
SDカードを挿したとき。
成功
hoge@fuga:~# dmesg | grep "mmcblk"
[ 2.263781] mmcblk mmc0:aaaa: no of_node; not parsing pinctrl DT
[ 2.265613] mmcblk0: mmc0:aaaa SL16G 14.8 GiB
[ 2.269669] mmcblk0: p1
エラー
hoge@fuga:~# dmesg | grep "mmcblk"
[ 2.264323] mmcblk mmc0:1234: no of_node; not parsing pinctrl DT
[ 2.265635] mmcblk0: mmc0:1234 SA16G 14.4 GiB
[ 2.268000] mmcblk0: p1
[ 16.043423] print_req_error: I/O error, dev mmcblk0, sector 8192
[ 16.049477] Buffer I/O error on dev mmcblk0p1, logical block 0, lost sync page write
[ 29.127348] print_req_error: I/O error, dev mmcblk0, sector 12692
[ 29.133562] Buffer I/O error on dev mmcblk0p1, logical block 4500, lost async page write
[ 29.142936] print_req_error: I/O error, dev mmcblk0, sector 16384
[ 29.149151] Buffer I/O error on dev mmcblk0p1, logical block 8192, lost async page write
[ 29.158802] print_req_error: I/O error, dev mmcblk0, sector 9000
[ 29.164846] Buffer I/O error on dev mmcblk0p1, logical block 808, lost async page write
[ 29.174049] print_req_error: I/O error, dev mmcblk0, sector 16704
[ 29.180168] Buffer I/O error on dev mmcblk0p1, logical block 8512, lost async page write
[ 29.188277] Buffer I/O error on dev mmcblk0p1, logical block 8513, lost async page write
[ 29.196382] Buffer I/O error on dev mmcblk0p1, logical block 8514, lost async page write
[ 29.204487] Buffer I/O error on dev mmcblk0p1, logical block 8515, lost async page write
[ 29.212591] Buffer I/O error on dev mmcblk0p1, logical block 8516, lost async page write
[ 29.220705] Buffer I/O error on dev mmcblk0p1, logical block 8517, lost async page write
[ 29.228818] Buffer I/O error on dev mmcblk0p1, logical block 8518, lost async page write
[ 29.238277] print_req_error: I/O error, dev mmcblk0, sector 8193
[ 239.536822] print_req_error: I/O error, dev mmcblk0, sector 9000
[ 239.543029] Buffer I/O error on dev mmcblk0p1, logical block 808, lost async page write
[ 239.551902] print_req_error: I/O error, dev mmcblk0, sector 12692
[ 239.558132] Buffer I/O error on dev mmcblk0p1, logical block 4500, lost async page write
[ 239.567829] print_req_error: I/O error, dev mmcblk0, sector 16704
[ 239.574106] Buffer I/O error on dev mmcblk0p1, logical block 8512, lost async page write
[ 239.583232] print_req_error: I/O error, dev mmcblk0, sector 16896
[ 239.589458] Buffer I/O error on dev mmcblk0p1, logical block 8704, lost async page write
[ 239.597644] Buffer I/O error on dev mmcblk0p1, logical block 8705, lost async page write
[ 239.605801] Buffer I/O error on dev mmcblk0p1, logical block 8706, lost async page write
[ 239.613962] Buffer I/O error on dev mmcblk0p1, logical block 8707, lost async page write
[ 239.622105] Buffer I/O error on dev mmcblk0p1, logical block 8708, lost async page write
[ 239.630219] Buffer I/O error on dev mmcblk0p1, logical block 8709, lost async page write
[ 239.638486] Buffer I/O error on dev mmcblk0p1, logical block 8710, lost async page write
[ 239.647843] print_req_error: I/O error, dev mmcblk0, sector 16768
[ 239.655300] print_req_error: I/O error, dev mmcblk0, sector 17024
[ 239.664076] print_req_error: I/O error, dev mmcblk0, sector 8193
[ 239.670179] print_req_error: I/O error, dev mmcblk0, sector 16384
[ 239.677324] print_req_error: I/O error, dev mmcblk0, sector 16960
[ 239.683455] print_req_error: I/O error, dev mmcblk0, sector 16896
[ 249.708583] print_req_error: I/O error, dev mmcblk0, sector 17088
[ 249.716507] print_req_error: I/O error, dev mmcblk0, sector 8193
[ 249.722559] print_req_error: I/O error, dev mmcblk0, sector 9000
[ 249.722581] Buffer I/O error on dev mmcblk0p1, logical block 808, lost async page write
[ 249.736803] Buffer I/O error on dev mmcblk0p1, logical block 1, lost async page write
[ 249.745672] print_req_error: I/O error, dev mmcblk0, sector 12692
[ 249.751796] print_req_error: I/O error, dev mmcblk0, sector 17024
[ 249.751812] Buffer I/O error on dev mmcblk0p1, logical block 8832, lost async page write
[ 249.766156] Buffer I/O error on dev mmcblk0p1, logical block 4500, lost async page write
[ 259.791444] print_req_error: I/O error, dev mmcblk0, sector 17109
[ 259.797798] Buffer I/O error on dev mmcblk0p1, logical block 8917, lost async page write
[ 259.806008] Buffer I/O error on dev mmcblk0p1, logical block 8918, lost async page write
[ 259.814269] Buffer I/O error on dev mmcblk0p1, logical block 8919, lost async page write
[ 259.823526] print_req_error: I/O error, dev mmcblk0, sector 17024
[ 259.829771] Buffer I/O error on dev mmcblk0p1, logical block 8832, lost async page write
[ 266.856983] FAT-fs (mmcblk0p1): error, fat_get_cluster: invalid cluster chain (i_pos 141315)
[ 266.865528] FAT-fs (mmcblk0p1): Filesystem has been set read-only
[ 266.872571] FAT-fs (mmcblk0p1): error, fat_free: invalid cluster chain (i_pos 141315)
[ 266.881017] FAT-fs (mmcblk0p1): error, fat_get_cluster: invalid cluster chain (i_pos 141315)
[ 266.889741] FAT-fs (mmcblk0p1): error, fat_free: invalid cluster chain (i_pos 141315)
[ 268.255816] FAT-fs (mmcblk0p1): error, fat_get_cluster: invalid cluster chain (i_pos 141315)
[ 268.264630] FAT-fs (mmcblk0p1): error, fat_free: invalid cluster chain (i_pos 141315)
[ 269.858137] print_req_error: I/O error, dev mmcblk0, sector 17135
[ 269.864602] Buffer I/O error on dev mmcblk0p1, logical block 8943, lost async page write
[ 269.874095] print_req_error: I/O error, dev mmcblk0, sector 9000
[ 269.880309] Buffer I/O error on dev mmcblk0p1, logical block 808, lost async page write
[ 269.889609] print_req_error: I/O error, dev mmcblk0, sector 12692
[ 269.896019] Buffer I/O error on dev mmcblk0p1, logical block 4500, lost async page write
[ 269.905515] print_req_error: I/O error, dev mmcblk0, sector 17024
[ 269.911878] Buffer I/O error on dev mmcblk0p1, logical block 8832, lost async page write
[ 269.921618] print_req_error: I/O error, dev mmcblk0, sector 8193
[ 269.927857] Buffer I/O error on dev mmcblk0p1, logical block 1, lost async page write
hoge@fuga:~#