| /* |
| * Copyright 2014 Broadcom Corporation. |
| * |
| * SPDX-License-Identifier: GPL-2.0+ |
| */ |
| |
| 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 |
| http://www.arm.com/products/tools/models/fast-models/foundation-model.php) |
| 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 |
| environment variable. |
