shell cmd msdosfmt a NOOP (in 4.9.1) for SD/MMC

Chris Johns chrisj at
Sat Jan 24 00:01:15 UTC 2009

Gene Smith wrote:
> I tried the shell command msdosfmt again on my MMC and still nothing 
> happens. I thought I had all my drivers working OK. It gets to the point 
> in the format code where it wants to write a block to flash but the 
> "write_entry" for the driver is NULL so nothing happens. However, no 
> error is flagged so the shell still prints "formatting successful."
> The write_entry is the NULL entry for sd_card_disk_ops in spi-sd-card.c. 
> When I change it from NULL and set it to sd_card_driver_write (a 
> function in the same file that I had never seen called) msdosfmt 
> attempts to do the write of the block with this function.
> However, it still fails inside sd_card_driver_write(). I think because 
> the driver table "e" that it gets with the call to 
> sd_card_driver_get_entry() is bad since the "major number" is 8 (a 2nd 
> instance) instead of "major number" 9 (the first instance with the flash 
> info set correctly). This kludge fixes it inside 4.9.1's 
> sd_card_driver_write():
> 	/* Get driver entry */
> #if 0
> 	rv = sd_card_driver_get_entry(minor, &e);
> 	CHECK_RVSC( rv, "Get driver entry");
> #else
> 	e = &sd_card_driver_table[0];
> #endif
> 	/* Start */
> 	sc = sd_card_start(e);   <---this failed with #if 0 code!
> I made the same change in sd_card_driver_read(), not sure if it is called.
> Looking at the HEAD version of spi-sd-card.c, I see it has been changed 
> so that there would only be a single "major" instance generated per bus 
> device (in my case one SPI device).  Also functions 
> sd_card_driver_write/read() are removed from HEAD. However, the 
> "write_entry" function is now rtems_blkdev_generic_write (not defined in 
> 4.9.1). Hopefully the correct function will be called when msdosfmt code 
> calls rtems_blkdev_generic_write().

Maybe these threads will help explain what has changed:

Given what you say I suspect the CVS version will format the card.


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