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doc/README.semihosting
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SPDX-License-Identifier: GPL-2.0+ |
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/* * Copyright 2014 Broadcom Corporation. |
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*/ 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. |
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The semihosting code adds a command: |
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smhload <image> <address> [env var] |
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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. |