memory directly available to loader(8) and friends was limited to 640K on i386.
Those times have passed long time ago and now loader(8) can directly access
up to 4GB of RAM at least theoretically. At the same time, there are several
places where it's assumed that malloc() will only allocate memory within
first megabyte.
Remove that assumption by allocating appropriate bounce buffers for BIOS
calls on stack where necessary.
This allows using memory above first megabyte for heap if necessary.
things over floppy size limits, I can exclude it for release builds or
something like that. Most of the changes are to get the load_elf.c file
into a seperate elf32_ or elf64_ namespace so that you can have two
ELF loaders present at once. Note that for 64 bit kernels, it actually
starts up the kernel already in 64 bit mode with paging enabled. This
is really easy because we have a known minimum feature set.
Of note is that for amd64, we have to pass in the bios int 15 0xe821
memory map because once in long mode, you absolutely cannot make VM86
calls. amd64 does not use 'struct bootinfo' at all. It is a pure loader
metadata startup, just like sparc64 and powerpc. Much of the
infrastructure to support this was adapted from sparc64.
