[Ilugc] Query on drivers?
- From: shuveb@xxxxxxxxx (Shuveb Hussain)
- Date: Tue Aug 23 10:50:06 2005
Hi,
Assuming that the user space mem can be made not to swap out.
We cant assume this :(
Then virtual memory would not be possible to implement. Remember,
virtual memory is not just about adding swap space and increasing the
amount of memory that processes can use. VM also gives you the
flexibility to map arbitary pages into any address you please thru the
memory mapping tables. Think about sharing text segments of large
programs that are being run by different users on the same system.
Especially when you consider DMA from devices to RAM, there are many
restrictions that apply. So this route has to be taken. The DMA system
does not "see" the mapping tables. It sees physical addresses,
untranslated.
--shuveb
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