Sundance SMT6025 v.2.9 - Manual (Page 24)

Version 2.9 Page 24 of 45 SMT6025 User Manual
15.4.2 Host memory
The host can lock down a region of its memory and make this available
to the DSP over the PCI bus. The host memory needs to be locked
down in order for the DSP to safely gain access this memory. The host
places Information necessary for the DSP to access this memory in a
section of the carrier board’s SRAM reserved for this purpose. This
information is known as a memory descriptor list (MDL), and each MDL
can describe an area of host memory up to 16MB in size. There is one
MDL for each HSC.
The host operating system will not page to disk any locked down
memory, and will ensure that the memory remains at a fixed physical
location.
Channel 0 MDL
Channel 1 MDL
Channel 2 MDL
Channel 3 MDL
Channel 4 MDL
Channel 5 MDL
Channel 6 MDL
Channel 7 MDL
0x00000
0x20000
0x40000
0x60000
0x80000
0xA0000
0xC0000
0xE0000
Byte offset
64KB Area for
MDL
64KB SRAM
argument area
SRAM memory
Figure 8 - Layout of the SRAM memory
15.5 Channel handler
A channel handler is software that runs on the host and performs actions on
behalf of the DSP. Figure 9 describes the operation of a handler.
User Manual (QCF42); Version 2.9, 22/02/02; © Sundance Multiprocessor Technology Ltd. 2002