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- /*
- * 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.
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