- Created driver framework with probe/init lifecycle. Drivers register via
REGISTER_DRIVER macro which places pointers in a .drivers linker section.
- During boot, init_drivers() iterates the section, probes each driver
(checking if hardware is present), and initializes those that respond OK.
- Added .drivers section to linker.ld with __drivers_start/__drivers_end
symbols for iteration.
- Also added .rodata.* pattern to the .rodata section for string literals
placed in sub-sections by the compiler.
- No drivers are registered yet; the VGA driver will be the first.
Tested: boots cleanly with driver scan completing (0 registered, 0 loaded).
- Added bitmap-based physical memory manager (PMM) that parses the Multiboot2
memory map to discover available RAM regions.
- Supports two allocation zones: PMM_ZONE_DMA (below 16MB) and PMM_ZONE_NORMAL
(above 16MB), with automatic fallback from NORMAL to DMA when the preferred
zone is exhausted.
- Marks kernel memory region and multiboot info structure as reserved using
_kernel_start/_kernel_end linker symbols.
- Page 0 is always marked as used to prevent returning NULL as a valid address.
- Added linker script symbols (_kernel_start, _kernel_end) to track kernel
memory boundaries for the allocator.
- Kernel now initializes PMM after PIC and performs test allocations to verify
the subsystem works.
