my device is xylinx zynq ultrascale zcu106 evk.
and i reserve 4GB of DDR memory for specific usage.
this area is platform device and also controlled by character device driver.
if i want write data to physical storage immediately, open file with flag "O_SYNC".
fd = open("myfile",O_RDWR|O_SYNC);
also i can use these file i/o interface for control character device driver.
shell : mknod /dev/my_chrdev c 99 0
c program : fd = open("/dev/my_chrdev",O_RDWR|O_SYNC);
I want to know what effect it has when opening a character device node with the "O_SYNC" flag.
And how can I guarantee the cache coherent of i/o for the character device?.
Does the file io interface give feedback when a device node is opened through the sync flag in the user level application?