mirror of
https://github.com/AsahiLinux/u-boot
synced 2024-11-30 16:39:35 +00:00
202a674bb8
Instead of sprinkling custom code and calls over the Vexpress64
boardfile, create a command that loads images using semihosting
just like we would load from flash memory of over the network,
using a special command:
smhload <image> <address>
This will make it possible to remove some custom calls and
code and make the boot easier.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
39 lines
1.8 KiB
Text
39 lines
1.8 KiB
Text
/*
|
|
* 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.
|