Target hooks

[AndrewD]

This allows the target to supply custom target_init() and target_boot() functions, via a library linked with the bios. eg:

    # add custom target specific library to the bios:
    src="libtarget"
    src_dir = os.path.abspath(os.path.join(os.path.dirname(__file__), src))
    builder.add_software_package(src, src_dir)
    builder.add_software_library(src)

[enjoy-digital]

Thanks @AndrewD, this looks good. I'll review it soon.

[trabucayre]

why not something like:

void target_nop() {}
void target_init(void) __attribute__((weak, alias("target_nop")));
void target_boot(void) __attribute__((weak, alias("target_nop")));

to avoid having to test if function exist

[AndrewD]

Yes that's another alternative I onsidered.I like the fact that the test makes it's clear that it's optional, but that's personal preference.
There doesn't appear to have been any goal to minimise code size in the bios so i opted for clarity.

[trabucayre]

For target_boot and target_init I think its a good idea to allows target/specific libraries to do some tasks, at some points, without having to modify existing code.
But for check_image_in_flash and copy_image_from_flash_to_ram its less clear. Is it to allows custom code to check and load firmware for a custom boot mode more or less similar to flashboot() ?

[AndrewD]

But for check_image_in_flash and copy_image_from_flash_to_ram its less clear. Is it to allows custom code to check and load firmware for a custom boot mode more or less similar to flashboot() ?

Yes: for example a target_boot() that can validate a dtd, copy a kernel and copy then run opensbi is one such usage.

[AndrewD]

I would also like to rename for check_image_in_flash and copy_image_from_flash_to_ram but didn't to minimise the diff