Why MSI is limited to 32 MSI's per device

[valmiki]

Hi,

Why MSI interrupts are limited to 32 per device ?
We have 16 bit data, with which we can have 2^16 combinaitons of different
data, which in turn those many MSI vectors.

Other than increase in number interrupts to 2048 in MSI-X, what advantage we
get by using MSI-X over MSI.

I read MSI-X interrupts can be targeted to different CPU's in an SMP system.
why can't MSI interrupts can be targeted to different processors ?  


Thanks & Regards,
Valmiki