load and jump to stage 3 separately from stage 2

include/globals.s

@@ -1,5 +1,5 @@
-%ifndef BOOT_S1_VARS_H
-%define BOOT_S1_VARS_H
+%ifndef BOOT_GLOBALS_H
+%define BOOT_GLOBALS_H
 
 ; Stage 1 base stack frame variable offsets / globals
 ; (we use the same offsets once we copy the variables to the globals section)
@@ -23,6 +23,16 @@
 %define GPT_SECTOR_ENTRY_IDX   0x14
 %define GPT_SECTORS_LOADED     0x16
 %define GPT_CURRENT_LBA        0x18
+; 2-byte address of the partition GPT entry loaded into memory.
 %define STAGE_2_GPT_ENTRY_ADDR 0x1a
 
+; Stage 2 globals
+; -------------------------------------------------------------------------------------------------
+; 4-byte partition end LBA.
+%define LOADER_PART_END_LBA   0x1c
+; 2-byte stage 2 start LBA.
+%define STAGE_2_START_LBA      0x20
+; 2-byte stage 2 start LBA (inclusive).
+%define STAGE_2_END_LBA        0x22
+
 %endif