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

[Chris Johns]

Gene Smith wrote:
> 
> Yes, I think Robert S. Grimes was seeing his write to "absolute" sector 
> not work for the same reason. So if these "generic" functions are used 
> they are buffered by the cache during format, I think. Is that OK? 

Yes. The format command should have a cache flush as the end.

> Seems 
> like fmt should be done on an unmounted device and do immediate sector 
> writes?

The cache is just above the driver and caches blocks from the disk. It is 
multi-threaded so does not care who asks for what block. Mounting is a file 
system issue and relates to the contents of the blocks while the cache is only 
interested in the blocks. If everyone uses the cache everything is ok.

> But if it's OK, can the fixes to spi-sd-card.c from 1.7 to 1.8 
> be merged in to 1.6.2.1? Lots of changes in the diff. Otherwise, 
> msdosfmt of SD/MMC is broken on the 4.9 branch. Or my kluge is the fix?

Why not try what Joel suggests in his reply and take the code from CVS and see 
how it does ?

Regards
Chris