From Eric.Lowe at Sun.COM  Fri Oct 13 10:04:13 2006
From: Eric.Lowe at Sun.COM (Eric Lowe)
Date: Fri, 13 Oct 2006 12:04:13 -0500
Subject: [dmi-discuss] Thoughts on a quick prototype
Message-ID: <452FC70D.7080106@Sun.COM>

Here are some thoughts on how we could get this started.

- Allocate some large pages in userland using MPSS (4MB SPARC, 2MB Opteron)
- Pass the large pages down to a driver via an ioctl
- Introduce a beefed up version of ddi_umem_lock() which will allow the 
driver to lock the large user pages and return a scatter/gather list 
suitable for DMA.

Is this viable for a fast DMA prototype?

Creating the big pages in the kernel suitable for export to mmap() will 
be a bit messier, but possible; on Opteron, we might want to have a page 
reserve area (size settable via eeprom) for contiguous allocations in 
order to avoid fragmentation, which will eventually prevent 2M page 
allocations on a running system.

- Eric