From 4213fc2913722045eb2c327a64b99e3e3178aa5c Mon Sep 17 00:00:00 2001 From: Simon Glass Date: Sun, 24 Feb 2013 17:33:14 +0000 Subject: sandbox: Add un/map_sysmen() to deal with sandbox's ram_buf Sandbox doesn't actually provide U-Boot access to the machine's physical memory. Instead it provides a RAM buffer of configurable size, and all memory accesses are within that buffer. Sandbox memory starts at 0 and is CONFIG_DRAM_SIZE bytes in size. Allowing access outside this buffer might produce unpredictable results in the event of an error, and would expose the host machine's memory architecture to the sandbox U-Boot. Most U-Boot functions assume that they can just access memory at given address. For sandbox this is not true. Add a map_sysmem() call which converts a U-Boot address to a system address. In most cases this is a NOP, but for sandbox it returns a pointer to that memory inside the RAM buffer. To get a U-Boot feature to work correctly within sandbox, you should call map_sysmem() to get a pointer to the address, and then use that address for any U-Boot memory accesses. Signed-off-by: Simon Glass --- README | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'README') diff --git a/README b/README index 0070694438..51eb71b27c 100644 --- a/README +++ b/README @@ -3811,6 +3811,15 @@ Low Level (hardware related) configuration options: that is executed before the actual U-Boot. E.g. when compiling a NAND SPL. +- CONFIG_ARCH_MAP_SYSMEM + Generally U-Boot (and in particular the md command) uses + effective address. It is therefore not necessary to regard + U-Boot address as virtual addresses that need to be translated + to physical addresses. However, sandbox requires this, since + it maintains its own little RAM buffer which contains all + addressable memory. This option causes some memory accesses + to be mapped through map_sysmem() / unmap_sysmem(). + - CONFIG_USE_ARCH_MEMCPY CONFIG_USE_ARCH_MEMSET If these options are used a optimized version of memcpy/memset will -- cgit v1.2.3