[memmap] Define an API for managing the system memory map

Define a generic system memory map API, based on the abstraction
created for parsing the FDT memory map and adding a concept of hidden
in-use memory regions as required to support patching the BIOS INT 15
memory map.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/config/defaults/efi.h

@@ -16,6 +16,7 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 #define CONSOLE_EFI
 #define TIMER_EFI
 #define UMALLOC_EFI
+#define MEMMAP_NULL
 #define SMBIOS_EFI
 #define SANBOOT_EFI
 #define BOFM_EFI

src/config/defaults/linux.h

@@ -13,6 +13,7 @@ FILE_LICENCE ( GPL2_OR_LATER );
 #define TIMER_LINUX
 #define UACCESS_LINUX
 #define UMALLOC_LINUX
+#define MEMMAP_NULL
 #define NAP_LINUX
 #define SMBIOS_LINUX
 #define SANBOOT_DUMMY

src/config/defaults/pcbios.h

@@ -17,6 +17,7 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 #define CONSOLE_PCBIOS
 #define NAP_PCBIOS
 #define UMALLOC_MEMTOP
+#define MEMMAP_NULL
 #define SMBIOS_PCBIOS
 #define SANBOOT_PCBIOS
 #define ENTROPY_RTC

src/config/defaults/sbi.h

@@ -19,6 +19,7 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 #define CONSOLE_SBI
 #define REBOOT_SBI
 #define UMALLOC_SBI
+#define MEMMAP_NULL
 
 #define ACPI_NULL
 #define MPAPI_NULL