diff options
Diffstat (limited to 'Documentation/arm/porting.rst')
| -rw-r--r-- | Documentation/arm/porting.rst | 137 |
1 files changed, 0 insertions, 137 deletions
diff --git a/Documentation/arm/porting.rst b/Documentation/arm/porting.rst deleted file mode 100644 index bd21958bdb2d..000000000000 --- a/Documentation/arm/porting.rst +++ /dev/null @@ -1,137 +0,0 @@ -======= -Porting -======= - -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. |