Dma data is a byte stream..?

["Ashish anand" <ashish.anand@inspiretech.com>]

Hello,

I have a question regarding endianness bit in PCI bridge dma windiw
setting register.
regardless of this endianness bit setting my n/w card or other pci card
works..it can
only be possible if bus master treats the dma data as byte stream.

now questions are..
1> then why there is provision of a endiannness bit in pci bridge ..though
still i haven't
gone through the every bit of my manual.

2> if dma data is byte stream , then why there would be a aligmenmt
constraints for 
receive or transmit buffers in system memory..

Best Regards,
Ashish Anand