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| author | Linus Walleij <linus.walleij@linaro.org> | 2015-03-23 11:06:11 +0100 |
|---|---|---|
| committer | Tom Rini <trini@konsulko.com> | 2015-03-28 12:07:45 -0400 |
| commit | 202a674bb8b7d7867503224857a2b0e04617d9b3 (patch) | |
| tree | eb8cfaeb9ed0ce210212115c538323a255d53312 /doc/README.semihosting | |
| parent | e769f68613ee4f84c8e2aea784335df74ceea397 (diff) | |
| download | u-boot-imx-202a674bb8b7d7867503224857a2b0e04617d9b3.zip u-boot-imx-202a674bb8b7d7867503224857a2b0e04617d9b3.tar.gz u-boot-imx-202a674bb8b7d7867503224857a2b0e04617d9b3.tar.bz2 | |
armv8: semihosting: add a command to load semihosted images
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>
Diffstat (limited to 'doc/README.semihosting')
| -rw-r--r-- | doc/README.semihosting | 25 |
1 files changed, 5 insertions, 20 deletions
diff --git a/doc/README.semihosting b/doc/README.semihosting index 7248560..c016a4f 100644 --- a/doc/README.semihosting +++ b/doc/README.semihosting @@ -30,25 +30,10 @@ 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 level of semihosting support is minimal, restricted to just what it -takes to load images to memory. If more semihosting functionality is -required, such as file seek, outputting strings, reading characters, etc, -then it can be easily added later. +The semihosting code adds a command: -We require that the board include file define these env variables: -- kernel_name e.g. "uImage" -- kernel_addr_r e.g. "0x80000000" -- initrd_name e.g. "ramdisk.img" -- initrd_addr_r e.g. "0x88000000" -- fdt_name e.g. "devtree.dtb" -- fdt_addr_r e.g. "0x83000000" + smhload <image> <address> [env var] -Optionally, "fdt_high" and "initrd_high" can be specified as per -their rules for allowing or preventing copying of these images. - -For the "fdt chosen" startup macro, this code will then define: -- initrd_end (based on retrieving initrd_addr_r plus actual initrd_size) - -We will then load the kernel, initrd, and fdt into the specified -locations in memory in a similar way that the ATF fastmodel code -uses semihosting calls to load other boot stages and u-boot itself. +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. |