Remove ELF and initrd loading from the kernel. The bootloader now loads
the initial programs, as it does with the kernel. Other files that were
in the initrd are now on the ESP, and non-program files are just passed
as modules.
There were a few lingering bugs due to places where 510/511 were
hard-coded as the kernel-space PML4 entries. These are now constants
defined in kernel_memory.h instead.
Tags: boot memory paging
* When using the non-allocating version of `get_uefi_mappings` the
length was not getting set. Reworked this function.
* Having `build_kernel_mem_map` from `bootloader_main_uefi` caused it to
get an out of date map key. Moved this function into `efi_main` right
before exiting boot services.
Set up initial page tables for both the offset-mapped area and the
loaded kernel code and data.
* Got rid of the `loaded_elf` struct - the loader now runs after the
initial PML4 is created and maps the ELF sections itself.
* Copied in the `page_table` and `page_table_indices` from the kernel,
still need to clean this up and extract it into shared code.
* Added `page_table_cache` to the kernel args to pass along free pages
that can be used for initial page tables.
Tags: paging
The `build_kernel_mem_map` function now calls `get_uefi_mappings`
itself, instead of having the efi map passed in. `get_uefi_mappings`
also now takes a `bool allocate` to direct it to actually allocate
the map or not. If it doesn't, it instead just returns the size of
the map and the metadata - which `build_kernel_mem_map` uses to decide
how much space to first allocate for the kernel's map.
Exiting boot services can't actually be done from inside
`bootloader_uefi_main`, because there are objects in that scope that run
code requiring boot services in their destructors.
Also added `support.cpp` with `memcpy` because clang will emit
references to `memcpy` even in freestanding mode.
Added a `debug_break` function to allow for faking breakpoints when
connecting to the bootloader with GDB.
Tags: debug
The `get_mappings()` function was getting too large, and some of its
output is needed by more than just the building of the kernel map. Split
it out into two.
Tags: boot memory
- The old kernel_args structure is now mostly represented as a series of
'modules' or memory ranges, tagged with a type. An arbitrary number
can be passed to the kernel
- Update bootloader to allocate space for the args header and 10 module
descriptors
Removed the frame allocation logic from page_manager and replaced it
with using an instance of frame_allocator instead. This had several
major ripple effects:
- memory_initalize() had to change to support this new world
- Where to map used blocks is now passed as a flag, since blocks don't
track their virtual address anymore
- Instead of the complicated "find N contiguous pages that can be
mapped in with one page table", we now just have the bootloader give
us some (currently 64) pages to use both for tables and scratch
space.
- frame_allocator initialization was split into two steps to allow
mapping used blocks before std::move()ing them over
