boot from NAND vs SD

1. from the DSP point of view , NAND　flash is mapped to DSP Address space.
2. databus
NAND 8-bit , 16-bit
SD 1-bit, 4/8bit

3. file system
NAND : jffs2(compressed)
SD : ext2/3(uncompressed), better preformance

NAND flash ought to be a lot faster than Glamo's MMC interface. Where is
the bug? FWIW, I tried a simple hdparm run on NOR flash, NAND flash and SD
card:

r...@debian-gta02:~# hdparm --direct -t /dev/mtdblock0 # NOR flash

/dev/mtdblock0:
Timing O_DIRECT disk reads: 2 MB in 1.24 seconds = 1.61 MB/sec

r...@debian-gta02:~# hdparm --direct -t /dev/mtdblock3 # NAND flash

/dev/mtdblock3:
Timing O_DIRECT disk reads: 8 MB in 2.89 seconds = 2.77 MB/sec

r...@debian-gta02:~# hdparm --direct -t /dev/mmcblk0 # Glamo MMC

/dev/mmcblk0:
Timing O_DIRECT disk reads: 8 MB in 3.46 seconds = 2.31 MB/sec