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author | 2005-04-16 15:20:36 -0700 | |
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committer | 2005-04-16 15:20:36 -0700 | |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /Documentation/arm/Porting | |
download | linux-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.gz linux-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.bz2 linux-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.zip |
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
Diffstat (limited to 'Documentation/arm/Porting')
-rw-r--r-- | Documentation/arm/Porting | 135 |
1 files changed, 135 insertions, 0 deletions
diff --git a/Documentation/arm/Porting b/Documentation/arm/Porting new file mode 100644 index 000000000000..a492233931b9 --- /dev/null +++ b/Documentation/arm/Porting @@ -0,0 +1,135 @@ +Taken from list archive at http://lists.arm.linux.org.uk/pipermail/linux-arm-kernel/2001-July/004064.html + +Initial definitions +------------------- + +The following symbol definitions rely on you knowing the translation that +__virt_to_phys() does for your machine. This macro converts the passed +virtual address to a physical address. Normally, it is simply: + + phys = virt - PAGE_OFFSET + PHYS_OFFSET + + +Decompressor Symbols +-------------------- + +ZTEXTADDR + Start address of decompressor. There's no point in talking about + virtual or physical addresses here, since the MMU will be off at + the time when you call the decompressor code. You normally call + the kernel at this address to start it booting. This doesn't have + to be located in RAM, it can be in flash or other read-only or + read-write addressable medium. + +ZBSSADDR + Start address of zero-initialised work area for the decompressor. + This must be pointing at RAM. The decompressor will zero initialise + this for you. Again, the MMU will be off. + +ZRELADDR + This is the address where the decompressed kernel will be written, + and eventually executed. The following constraint must be valid: + + __virt_to_phys(TEXTADDR) == ZRELADDR + + The initial part of the kernel is carefully coded to be position + independent. + +INITRD_PHYS + Physical address to place the initial RAM disk. Only relevant if + you are using the bootpImage stuff (which only works on the old + struct param_struct). + +INITRD_VIRT + Virtual address of the initial RAM disk. The following constraint + must be valid: + + __virt_to_phys(INITRD_VIRT) == INITRD_PHYS + +PARAMS_PHYS + Physical address of the struct param_struct or tag list, giving the + kernel various parameters about its execution environment. + + +Kernel Symbols +-------------- + +PHYS_OFFSET + Physical start address of the first bank of RAM. + +PAGE_OFFSET + Virtual start address of the first bank of RAM. During the kernel + boot phase, virtual address PAGE_OFFSET will be mapped to physical + address PHYS_OFFSET, along with any other mappings you supply. + This should be the same value as TASK_SIZE. + +TASK_SIZE + The maximum size of a user process in bytes. Since user space + always starts at zero, this is the maximum address that a user + process can access+1. The user space stack grows down from this + address. + + Any virtual address below TASK_SIZE is deemed to be user process + area, and therefore managed dynamically on a process by process + basis by the kernel. I'll call this the user segment. + + Anything above TASK_SIZE is common to all processes. I'll call + this the kernel segment. + + (In other words, you can't put IO mappings below TASK_SIZE, and + hence PAGE_OFFSET). + +TEXTADDR + Virtual start address of kernel, normally PAGE_OFFSET + 0x8000. + This is where the kernel image ends up. With the latest kernels, + it must be located at 32768 bytes into a 128MB region. Previous + kernels placed a restriction of 256MB here. + +DATAADDR + Virtual address for the kernel data segment. Must not be defined + when using the decompressor. + +VMALLOC_START +VMALLOC_END + Virtual addresses bounding the vmalloc() area. There must not be + any static mappings in this area; vmalloc will overwrite them. + The addresses must also be in the kernel segment (see above). + Normally, the vmalloc() area starts VMALLOC_OFFSET bytes above the + last virtual RAM address (found using variable high_memory). + +VMALLOC_OFFSET + Offset normally incorporated into VMALLOC_START to provide a hole + between virtual RAM and the vmalloc area. We do this to allow + out of bounds memory accesses (eg, something writing off the end + of the mapped memory map) to be caught. Normally set to 8MB. + +Architecture Specific Macros +---------------------------- + +BOOT_MEM(pram,pio,vio) + `pram' specifies the physical start address of RAM. Must always + be present, and should be the same as PHYS_OFFSET. + + `pio' is the physical address of an 8MB region containing IO for + use with the debugging macros in arch/arm/kernel/debug-armv.S. + + `vio' is the virtual address of the 8MB debugging region. + + It is expected that the debugging region will be re-initialised + by the architecture specific code later in the code (via the + MAPIO function). + +BOOT_PARAMS + Same as, and see PARAMS_PHYS. + +FIXUP(func) + Machine specific fixups, run before memory subsystems have been + initialised. + +MAPIO(func) + Machine specific function to map IO areas (including the debug + region above). + +INITIRQ(func) + Machine specific function to initialise interrupts. + |