On Wed, Mar 12, 2014 at 09:04:01AM -0700, Darwin Rambo wrote: > The reason for this change is to be able to use the ARM Trusted Firmware > (ATF) to load the various ATF images, plus u-boot, which can then load > the kernel/ramdisk/dtb with calls to an external host from a standard > fastmodel armv8 board file using semihosting, and then launch the kernel > without a bootwrapper. This gives us a more realistic boot sequence. > > Rather than create a new armv8 board similar to armltd/vexpress64, add > semihosting calls to the existing one, enabled with CONFIG_SEMIHOSTING. > Also add a new board config file vexpress_aemv8a_semi.h. This change is > tested and works on the ARM foundation model. > > Support for armv7 in fastmodel is less useful due to the wide range of > available silicon but this change contains an untested armv7 placeholder > if desired. > > 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. > > Signed-off-by: Darwin Rambo <[email protected]>
At the high-level, I'm fine with this. But as an implementation detail
we need to either leverage vexpress_common.h or create a
vexpress_arm64_common.h or something. There's a lot in common between
these two configs, and some further clean-up we need to do to the first
one anyhow.
Next:
> +#ifdef CONFIG_BOARD_LATE_INIT
> +int board_late_init(void)
> +{
> +#ifdef CONFIG_SEMIHOSTING
> +
> + /*
> + * We require that the board include file defines these env variables:
> + * - kernel_addr
> + * - initrd_addr
> + * - fdt_addr
> + *
> + * For the "fdt chosen" startup macro, this code will then define:
> + * - initrd_end (based on initrd_base 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.
> + */
> +
> + /* Env variable strings */
> + char *kernel_addr_str = getenv("kernel_addr");
> + char *initrd_addr_str = getenv("initrd_addr");
> + char *fdt_addr_str = getenv("fdt_addr");
> + char initrd_end_str[64];
First, we need to document this stuff in a README file as well. Second,
I'd like to see kernel_addr_r / ramdisk_addr_r / fdt_addr_r used to
match-up with what Dennis Gilmore has been working on to get a common
env working.
[snip]
> + /* Assumes kernel is lower in memory than fdt */
> + smh_load(CONFIG_KNLNAME, kernel_addr, fdt_addr - kernel_addr, 1);
> +
> + /* Load fdt to memory */
> + smh_load(CONFIG_FDTNAME, fdt_addr, 0x20000, 1);
> +
> + /* Load initrd to memory */
> + smh_load(CONFIG_RDNAME, initrd_addr, initrd_size, 1);
Is there a reason we can't also get these from the environment? Or a
limitation of (how we support) the simulator that we don't have
persistent r/w environment right now?
Thanks!
--
Tom
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