> > The compact flash device may not support the sync command.  If this is
> > the case add "sync=ignore" to the command-line

You probably don't mean this.  "ignore" will not only not SC_SYNC but will also not drain dirty blocks from the io-blk 
cache (if delwri != 0).  It is intended for use with a UPS where you can cleanly unmount; in all other cases it will 
almost certainly lead to lost data.  "sync=optional" is the relevant option here; this will try SC_SYNC but won't get 
upset if this is unsupported (the onus is on you as the user of that option to know the h/w does not need this).

p.s. yes, the docs were wrong, they've been corrected and now read:
"
sync=mode
    Specify the required disk synchronization capability. The mode mode must be one of the following:

        * mandatory (the default) — the drive must support synchronisation to allow a filesystem to be mounted read/
write. If it doesn't, the mount fails and returns EROFS. A read-only mount (mount -r) can always be performed on any 
device.
        * optional — attempt synchronization, but ignore any error if the drive doesn't support such an operation. The 
driver might be incorrectly advertising the capabilities, or the physical media might not require explicit 
synchronization (write-through).
        * ignore — never issue a sychronization command to the disk, and don't drain dirty blocks from the fileystem 
cache (until an explicit umount). This mode is suitable only for use with a UPS.
"