egos-2k+ memory layout
(updated 09/01/2023)


HIGH MEM ADDR
------- +----------------------+ <- 0x8040_0000
        |                      |    [FREE_MEM_END]
 DTIM   | free memory          |
memory  | (4MB - 16KB)         |
 (4MB)  +----------------------+ <- 0x8000_4000
        | earth interface      |    [FREE_MEM_START]
        | (128B)               |
        +----------------------+ <- 0x8000_3f80
        | earth/grass stack    |    [GRASS_STACK_TOP]
        | (~8KB)               |
        \/\/\/\/\/\/\/\/\/\/\/\/

        /\/\/\/\/\/\/\/\/\/\/\/\
        | grass interface      |
        +----------------------+ <- 0x8000_2000
        | app stack            |    [APPS_STACK_TOP]
        | (6KB)                |
        +----------------------+ <- 0x8000_0800
        | system call args     |
        | (1KB)                |
        +----------------------+ <- 0x8000_0400
        | app args             |    [SYSCALL_ARG]
        | (1KB)                |
------- +----------------------+ <- 0x8000_0000
                                    [APPS_ARG]

        ...
------- +----------------------+ <- 0x20c0_0000
        | read-only fs w/      |
        | dirs & user app elfs |
        | (2MB)                |
        +----------------------+ <- 0x20a0_0000
 disk   | grass elf and        |
 image  | sys app elfs         |
 (4MB)  | (1MB)                |
        +----------------------+ <- 0x2090_0000
        | (1MB)                |
------- +----------------------+ <- 0x2080_0000
 boot   |                      |
 ROM    | earth code           |
 (4MB)  |                      |
------- +----------------------+ <- 0x2040_0000

        ...
    
------- +----------------------+ <- 0x1001_4000
        |                      |
 UART0  |                      |
 (4KB)  |                      |
        |                      |
------- +----------------------+ <- 0x1001_3000

        ...
------- +----------------------+ <- 0x0a00_0000
        |                      |    [ITIM_END]
        \/\/\/\/\/\/\/\/\/\/\/\/

        /\/\/\/\/\/\/\/\/\/\/\/\
        |                      |
        +----------------------+ <- 0x0820_4000
 ITIM   | app code+data        |    [APPS_ENTRY+APPS_SIZE]
 (32MB) | (16KB)               |
        +----------------------+ <- 0x0820_0000
        | grass code+data      |    [APPS_ENTRY]
        | (1 MB)               |
        +----------------------+ <- 0x0810_0000
        | earth data           |    [GRASS_ENTRY]
        | (1 MB)               |
------- +----------------------+ <- 0x0800_0000
                                    [ITIM_START]

...

------- +----------------------+ <- 0x0201_0000
        |                      |
        +----------------------+
        | mtime (8B)           |
 CLINT  +----------------------+ <- 0x0200_bff8
 (64KB) |                      |
        +----------------------+
        | mtimecp (8B)         |
        +----------------------+ <- 0x0200_4000
        |                      |
        +----------------------+
        | msip (4B)            |
------- +----------------------+ <- 0x0200_0000
LOW MEM ADDR