case:
when system is running well ,sudden tf became read-only;
analyze:
read the kernel log using dmesg , find follow log:
FAT-fs (mmcblk0p1): error, clusters badly computed (59 != 58)
FAT-fs (mmcblk0p1): Filesystem has been set read-only
what happen:
when we writing to tf card , tf card have bad clusters , so filesystem been set read-only.
solution:
umout tf card , the remount tf card, that can solution.
when we can't write to tf card , we can find the problem,
first ： judge the file system is writabe from /proc/mount
second : maybe tf card none free space. thought : df -h