Intel® 460GX Chipset Software Developer’s Manual
5-7
Memory Subsystem
5.5.3
Hardware Initialization
In order to decrease boot time of systems with large amounts of DRAM installed, hardware
initialization of memory will be supported. Since multiple rows will be initialized simultaneously,
the memory system will be able to initialize to 0 about 8 times faster than having the processor
looping through memory with writes. The MDC will force all zeroes on the data lines, with good
ECC, and the MAC will cycle through the memory addresses generating writes. The main limiter
to the number of rows being simultaneously initialized is current draw on the DRAM. One row
from each of the 4 stacks across the 2 cards will be initialized concurrently.
5.5.4
Memory Scrubbing
Scrubbing is the operation of walking through all installed DRAM and looking for errors. Each line
is read and then written back, whether there is an error or not. Within the SAC there is an engine to
generate addresses to be placed in the memory queue. These addresses are placed directly into the
SAC memory queue and are not snooped on the system bus, nor are they checked for address
conflicts, since the read-modify-write is treated as an atomic operation.
A scrub address is generated every 65K (65536) clocks. For a system with 32 GB of memory, this
would walk through all memory every 3.2 days. The following table shows the approximate time to
scrub memory based on memory size. Scrubbing may be disabled through a configuration bit.
Table 5-4. Scrubbing Time
Memory Size
Time to Scrub
64 MB
10 minutes
128 MB
20 minutes
256 MB
40 minutes
512 MB
1.2 hours
1 GB
3 hours
2 GB
5 hours
4 GB
10 hours
8 GB
20 hours
16 GB
1.6 days
32 GB
3.2 days
64 GB
6.4 days
Summary of Contents for 460GX
Page 1: ...Intel 460GX Chipset System Software Developer s Manual June 2001 Document Number 248704 001 ...
Page 20: ...Introduction 1 8 Intel 460GX Chipset Software Developer s Manual ...
Page 80: ...System Architecture 3 8 Intel 460GX Chipset Software Developer s Manual ...
Page 90: ...System Address Map 4 10 Intel 460GX Chipset Software Developer s Manual ...
Page 98: ...Memory Subsystem 5 8 Intel 460GX Chipset Software Developer s Manual ...
Page 146: ...AGP Subsystem 7 16 Intel 460GX Chipset Software Developer s Manual ...
Page 170: ...IFB Register Mapping 9 6 Intel 460GX Chipset Software Developer s Manual ...
Page 190: ...IFB Usage Considerations 10 20 Intel 460GX Chipset Software Developer s Manual ...
Page 232: ...LPC FWH Interface Configuration 11 42 Intel 460GX Chipset Software Developer s Manual ...
Page 244: ...IDE Configuration 12 12 Intel 460GX Chipset Software Developer s Manual ...
Page 258: ...Universal Serial Bus USB Configuration 13 14 Intel 460GX Chipset Software Developer s Manual ...
Page 270: ...SM Bus Controller Configuration 14 12 Intel 460GX Chipset Software Developer s Manual ...
Page 288: ...PCI LPC Bridge Description 15 18 Intel 460GX Chipset Software Developer s Manual ...
Page 294: ...IFB Power Management 16 6 Intel 460GX Chipset Software Developer s Manual ...