[microblaze-uclinux] problems with the file access to /dev/mtdblock0

["Brettschneider Falk" <fbrettschneider@xxxxxxxxxxxxxxx>]

Hi,
I access the flash partition directly by file IO interface without file system.
But I noticed the driver doesn't care about my desired synchronous I/O mode I've setup with parameter O_SYNC. I mean whenever I write data the writing is still cached (with cache size == flash sector size) and not really fully written to flash memory; also fsync() doesn't help. This looks like a driver bug to me. I found it out by activating the kernel logging of the MTD driver.

What can I do?


I use it this way:
  ...
  int fd = open("/dev/mtdblock0", O_RDWR | O_SYNC);	
  ...
  // read from flash
  lseek(fd, relAddr, SEEK_SET);
  read(fd, pReadInBuffer, size);
  ...
  // write to flash
  lseek(fd, relAddr, SEEK_SET);
  write(fd, pBufferToWrite, size);
  fsync(fd); // actually not necessary because of O_SYNC
  ...

The file will be opened at program start and will never be closed because of efficiency and further problems I experienced with closing and reopening of that driver.

Cheers,
 Falk

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