Load all sections to LMA not VMA, so the startup code(e.g. start.S) need
relocate .data section to the final address(VMA) and zero .bss section by self.
For example, SiFli and Actions: Background: Device with small sram,
Bootloader run in sram and psram, need boot to Application, with memory overlap
and without XIP. VMA of .data is in "psram" and LMA in "rom", if not enable
`ELF_LOADTO_LMA`, ELF loader will load the section to VMA (will fill bootloader
itself).
Signed-off-by: wangjianyu3 <wangjianyu3@xiaomi.com>
When the .elf file is loaded from disk, the kernel must be given write
access to the allocated .text section in the task's address environment.
The access is removed after the elf is loaded and relocations are done.
NOTE:
The reason this works for the ARM implementation, is that the ARM MMU
can be configured to give write access for the privileged mode, but
revoke write access for the user mode.
Regardless, it would be smart to revoke write access even for the
kernel, when the kernel does not need it. This framework allows doing
that, if someone wishes to take up the task.
* include: Introduce elf64.h and elf.h
Added elf64.h for 64bit ELF support and moved common definitions
from elf32.h to elf.h. Also introduced Elf_xxx to be used in
common libraries such as binfmt.
* binfmt, include, modlib, module: Add support for ELF64
Elf_xxx must be used instead of Elf32_xxx to support ELF64.
To use ELF64, CONFIG_ELF_64BIT must be enabled.
* binfmt, modlib: Add support for relocate address
* arch: risc-v: Add include/elf.h
* libs: machine: Add risc-v related files.
NOTE: Currently only supports ELF64
* boards: maix-bit: Add elf and posix_spawn configurations
* boards: maix-bit: Add support for module configuration
