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Message
From: christian@m...
Date: Thu, 30 Oct 2003 19:49:52 +0100
Subject: [openrisc] or1k, ram, rom
I have some questions about OR1200 (or OR1000) based-system.
1. Every peripheral (IP cores) is connected through a Wishbone
interface to correctly communicate with the openrisc processor. Is it
true?
2.
Address Space
0xf000_0000 - 0xffff_ffff Cached 256MB ROM
0xc000_0000 - 0xefff_ffff Cached 768MB Reserved
0xb800_0000 - 0xbfff_ffff Uncached 128MB Reserved for custom devices
0xa600_0000 - 0xb7ff_ffff Uncached 288MB Reserved
0x9c00_0000 - 0x9cff_ffff Uncached 16MB USB Host Controller 0-15
0x9b00_0000 - 0x9bff_ffff Uncached 16MB USB Func Controller 0-15
0x9600_0000 - 0x96ff_ffff Uncached 16MB PWM/Timer/Counter
Controller 0-15
0x9300_0000 - 0x93ff_ffff Uncached 16MB Memory Controller 0-15
0x9200_0000 - 0x92ff_ffff Uncached 16MB Ethernet Controller 0-15
0x9100_0000 - 0x91ff_ffff Uncached 16MB General-Purpose I/O 0-15
0x9000_0000 - 0x90ff_ffff Uncached 16MB UART16550 Controller 0-15
0x4000_0000 - 0x7fff_ffff Uncached 1GB Reserved
0x0000_0000 - 0x3fff_ffff Cached 1GB RAM
By reading some mails in this forum, the or1200 cpu reads, after reset,
the address 0x100 in rom space (in flash area). So, In fact, it has to
read the instructions from 0xf0000100? How is that possible? How the
address can be mapped into flash area? Is there any decoder that i
don't know?
3. How the H/W loading instructions? In fact, the BIOS is within the
0xf000000 area. It stores from rom into ram the OS kernel and it starts
the system initialization. It loads the driver... So the devices are maybe
described in a device table? Therefore, the OS reads it in order to
install the drivers.
My questions resides only about the H/W loading instructions and how
does the system to work correctly.
4. About the SDRAM, mainly the memories (Flash, SDRAM) must be
outside of the FPGA? And the cpu fetches instructions through the
memory controller?
About SDRAM, the memory access must be through another memory
controller?
Who is responsible to manage the memory space in the system?
I hope to understand everything now:)
Thank you
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