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diff --git a/Documentation/powerpc/SBC8260_memory_mapping.txt b/Documentation/powerpc/SBC8260_memory_mapping.txt deleted file mode 100644 index e6e9ee0506c..00000000000 --- a/Documentation/powerpc/SBC8260_memory_mapping.txt +++ /dev/null @@ -1,197 +0,0 @@ -Please mail me (Jon Diekema, diekema_jon@si.com or diekema@cideas.com) -if you have questions, comments or corrections. - - * EST SBC8260 Linux memory mapping rules - - http://www.estc.com/ - http://www.estc.com/products/boards/SBC8260-8240_ds.html - - Initial conditions: - ------------------- - - Tasks that need to be perform by the boot ROM before control is - transferred to zImage (compressed Linux kernel): - - - Define the IMMR to 0xf0000000 - - - Initialize the memory controller so that RAM is available at - physical address 0x00000000. On the SBC8260 is this 16M (64M) - SDRAM. - - - The boot ROM should only clear the RAM that it is using. - - The reason for doing this is to enhances the chances of a - successful post mortem on a Linux panic. One of the first - items to examine is the 16k (LOG_BUF_LEN) circular console - buffer called log_buf which is defined in kernel/printk.c. - - - To enhance boot ROM performance, the I-cache can be enabled. - - Date: Mon, 22 May 2000 14:21:10 -0700 - From: Neil Russell <caret@c-side.com> - - LiMon (LInux MONitor) runs with and starts Linux with MMU - off, I-cache enabled, D-cache disabled. The I-cache doesn't - need hints from the MMU to work correctly as the D-cache - does. No D-cache means no special code to handle devices in - the presence of cache (no snooping, etc). The use of the - I-cache means that the monitor can run acceptably fast - directly from ROM, rather than having to copy it to RAM. - - - Build the board information structure (see - include/asm-ppc/est8260.h for its definition) - - - The compressed Linux kernel (zImage) contains a bootstrap loader - that is position independent; you can load it into any RAM, - ROM or FLASH memory address >= 0x00500000 (above 5 MB), or - at its link address of 0x00400000 (4 MB). - - Note: If zImage is loaded at its link address of 0x00400000 (4 MB), - then zImage will skip the step of moving itself to - its link address. - - - Load R3 with the address of the board information structure - - - Transfer control to zImage - - - The Linux console port is SMC1, and the baud rate is controlled - from the bi_baudrate field of the board information structure. - On thing to keep in mind when picking the baud rate, is that - there is no flow control on the SMC ports. I would stick - with something safe and standard like 19200. - - On the EST SBC8260, the SMC1 port is on the COM1 connector of - the board. - - - EST SBC8260 defaults: - --------------------- - - Chip - Memory Sel Bus Use - --------------------- --- --- ---------------------------------- - 0x00000000-0x03FFFFFF CS2 60x (16M or 64M)/64M SDRAM - 0x04000000-0x04FFFFFF CS4 local 4M/16M SDRAM (soldered to the board) - 0x21000000-0x21000000 CS7 60x 1B/64K Flash present detect (from the flash SIMM) - 0x21000001-0x21000001 CS7 60x 1B/64K Switches (read) and LEDs (write) - 0x22000000-0x2200FFFF CS5 60x 8K/64K EEPROM - 0xFC000000-0xFCFFFFFF CS6 60x 2M/16M flash (8 bits wide, soldered to the board) - 0xFE000000-0xFFFFFFFF CS0 60x 4M/16M flash (SIMM) - - Notes: - ------ - - - The chip selects can map 32K blocks and up (powers of 2) - - - The SDRAM machine can handled up to 128Mbytes per chip select - - - Linux uses the 60x bus memory (the SDRAM DIMM) for the - communications buffers. - - - BATs can map 128K-256Mbytes each. There are four data BATs and - four instruction BATs. Generally the data and instruction BATs - are mapped the same. - - - The IMMR must be set above the kernel virtual memory addresses, - which start at 0xC0000000. Otherwise, the kernel may crash as - soon as you start any threads or processes due to VM collisions - in the kernel or user process space. - - - Details from Dan Malek <dan_malek@mvista.com> on 10/29/1999: - - The user application virtual space consumes the first 2 Gbytes - (0x00000000 to 0x7FFFFFFF). The kernel virtual text starts at - 0xC0000000, with data following. There is a "protection hole" - between the end of kernel data and the start of the kernel - dynamically allocated space, but this space is still within - 0xCxxxxxxx. - - Obviously the kernel can't map any physical addresses 1:1 in - these ranges. - - - Details from Dan Malek <dan_malek@mvista.com> on 5/19/2000: - - During the early kernel initialization, the kernel virtual - memory allocator is not operational. Prior to this KVM - initialization, we choose to map virtual to physical addresses - 1:1. That is, the kernel virtual address exactly matches the - physical address on the bus. These mappings are typically done - in arch/ppc/kernel/head.S, or arch/ppc/mm/init.c. Only - absolutely necessary mappings should be done at this time, for - example board control registers or a serial uart. Normal device - driver initialization should map resources later when necessary. - - Although platform dependent, and certainly the case for embedded - 8xx, traditionally memory is mapped at physical address zero, - and I/O devices above physical address 0x80000000. The lowest - and highest (above 0xf0000000) I/O addresses are traditionally - used for devices or registers we need to map during kernel - initialization and prior to KVM operation. For this reason, - and since it followed prior PowerPC platform examples, I chose - to map the embedded 8xx kernel to the 0xc0000000 virtual address. - This way, we can enable the MMU to map the kernel for proper - operation, and still map a few windows before the KVM is operational. - - On some systems, you could possibly run the kernel at the - 0x80000000 or any other virtual address. It just depends upon - mapping that must be done prior to KVM operational. You can never - map devices or kernel spaces that overlap with the user virtual - space. This is why default IMMR mapping used by most BDM tools - won't work. They put the IMMR at something like 0x10000000 or - 0x02000000 for example. You simply can't map these addresses early - in the kernel, and continue proper system operation. - - The embedded 8xx/82xx kernel is mature enough that all you should - need to do is map the IMMR someplace at or above 0xf0000000 and it - should boot far enough to get serial console messages and KGDB - connected on any platform. There are lots of other subtle memory - management design features that you simply don't need to worry - about. If you are changing functions related to MMU initialization, - you are likely breaking things that are known to work and are - heading down a path of disaster and frustration. Your changes - should be to make the flexibility of the processor fit Linux, - not force arbitrary and non-workable memory mappings into Linux. - - - You don't want to change KERNELLOAD or KERNELBASE, otherwise the - virtual memory and MMU code will get confused. - - arch/ppc/Makefile:KERNELLOAD = 0xc0000000 - - include/asm-ppc/page.h:#define PAGE_OFFSET 0xc0000000 - include/asm-ppc/page.h:#define KERNELBASE PAGE_OFFSET - - - RAM is at physical address 0x00000000, and gets mapped to - virtual address 0xC0000000 for the kernel. - - - Physical addresses used by the Linux kernel: - -------------------------------------------- - - 0x00000000-0x3FFFFFFF 1GB reserved for RAM - 0xF0000000-0xF001FFFF 128K IMMR 64K used for dual port memory, - 64K for 8260 registers - - - Logical addresses used by the Linux kernel: - ------------------------------------------- - - 0xF0000000-0xFFFFFFFF 256M BAT0 (IMMR: dual port RAM, registers) - 0xE0000000-0xEFFFFFFF 256M BAT1 (I/O space for custom boards) - 0xC0000000-0xCFFFFFFF 256M BAT2 (RAM) - 0xD0000000-0xDFFFFFFF 256M BAT3 (if RAM > 256MByte) - - - EST SBC8260 Linux mapping: - -------------------------- - - DBAT0, IBAT0, cache inhibited: - - Chip - Memory Sel Use - --------------------- --- --------------------------------- - 0xF0000000-0xF001FFFF n/a IMMR: dual port RAM, registers - - DBAT1, IBAT1, cache inhibited: - |