| * Copyright 2014 Broadcom Corporation.
|Semihosting is ARM's way of having a real or virtual target communicate
|with a host or host debugger for basic operations such as file I/O,
|console I/O, etc. Please see
|http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0471c/Bgbjjgij.html for more information.
|For developing on armv8 virtual fastmodel platforms, semihosting is a
|valuable tool since it allows access to image/configuration files before
|eMMC or other NV media are available.
|There are two main ARM virtual Fixed Virtual Platform (FVP) models,
|Versatile Express (VE) FVP and BASE FVP (See
|The initial vexpress64 u-boot board created here runs on the VE virtual
|platform using the license-free Foundation_v8 simulator. Fortunately,
|the Foundation_v8 simulator also supports the BASE_FVP model which
|companies can purchase licenses for and contain much more functionality.
|So we can, in u-boot, run either model by either using the VE FVP (default),
|or turning on CONFIG_BASE_FVP for the more full featured model.
|Rather than create a new armv8 board similar to armltd/vexpress64, add
|semihosting calls to the existing one, enabled with CONFIG_SEMIHOSTING
|and CONFIG_BASE_FVP both set. Also reuse the existing board config file
|vexpress_aemv8a.h but differentiate the two models by the presence or
|absence of CONFIG_BASE_FVP. This change is tested and works on both the
|Foundation and Base fastmodel simulators.
|The semihosting code adds a command:
| smhload <image> <address> [env var]
|That will load an image from the host filesystem into RAM at the specified
|address and optionally store the load end address in the specified