diff options
| author | Simon Glass <sjg@chromium.org> | 2013-02-24 17:33:14 +0000 |
|---|---|---|
| committer | Simon Glass <sjg@chromium.org> | 2013-02-28 19:09:22 -0800 |
| commit | 4213fc2913722045eb2c327a64b99e3e3178aa5c (patch) | |
| tree | af5c64aebc9d51c61a2990db7b5b3d66afcb42a8 /README | |
| parent | e101550a9a8b956434cf2a73f66afbb42f4654bd (diff) | |
| download | u-boot-4213fc2913722045eb2c327a64b99e3e3178aa5c.tar.gz | |
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 <sjg@chromium.org>
Diffstat (limited to 'README')
| -rw-r--r-- | README | 9 |
1 files changed, 9 insertions, 0 deletions
@@ -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 |