Memory layout
ARM11 Physical memory regions
| Address | Size | Description |
|---|---|---|
| 0x0 | 0x10000 | Bootrom (super secret code/data @ 0x8000) |
| 0x10000 | 0x10000 | Bootrom mirror |
| 0x10000000 | ? | IO memory |
| 0x17E00000 | 0x2000 | MPCore private memory region |
| 0x18000000 | 0x600000 | VRAM |
| 0x1FF00000 | 0x80000 | DSP memory |
| 0x1FF80000 | 0x80000 | AXI WRAM |
| 0x20000000 | 0x8000000 | FCRAM |
Memory map by firmware
ARM11 Detailed physical memory map
18000000 - 18600000: VRAM 1FF80000 - 1FFAB000: Kernel code 1FFAB000 - 1FFF0000: SlabHeap [temporarily contains boot processes] 1FFF0000 - 1FFF1000: ? 1FFF1000 - 1FFF2000: ? 1FFF2000 - 1FFF3000: ? 1FFF3000 - 1FFF4000: ? 1FFF4000 - 1FFF5000: Exception vectors 1FFF5000 - 1FFF5800: Unused? 1FFF5800 - 1FFF5C00: 256-entry L2 MMU table for VA FF4xx000 1FFF5C00 - 1FFF6000: 256-entry L2 MMU table for VA FF5xx000 1FFF6000 - 1FFF6400: 256-entry L2 MMU table for VA FF6xx000 1FFF6400 - 1FFF6800: 256-entry L2 MMU table for VA FF7xx000 1FFF6800 - 1FFF6C00: 256-entry L2 MMU table for VA FF8xx000 1FFF6C00 - 1FFF7000: 256-entry L2 MMU table for VA FF9xx000 1FFF7000 - 1FFF7400: 256-entry L2 MMU table for VA FFAxx000 1FFF7400 - 1FFF7800: 256-entry L2 MMU table for VA FFBxx000 1FFF7800 - 1FFF7C00: MMU table but unused? 1FFF7C00 - 1FFF8000: 256-entry L2 MMU table for VA FFFxx000 1FFF8000 - 1FFFC000: 4096-entry L1 MMU table for VA xxx00000 (CPU 0) 1FFFC000 - 20000000: 4096-entry L1 MMU table for VA xxx00000 (CPU 1) 20000000 - 28000000: Main memory
ARM11 Detailed virtual memory map
(valid only for FW0B, see Memory map by firmware for subsequent versions)
E8000000 - E8600000: mapped VRAM (18000000 - 18600000) EFF00000 - F0000000: mapped Internal memory (1FF00000 - 20000000) F0000000 - F8000000: mapped Main memory FF401000 - FF402000: mapped ? (27FC7000 - 27FC8000) FF403000 - FF404000: mapped ? (27FC2000 - 27FC3000) FF405000 - FF406000: mapped ? (27FBB000 - 27FBC000) FF407000 - FF408000: mapped ? (27FB3000 - 27FB4000) FF409000 - FF40A000: mapped ? (27F8E000 - 27F8F000) FFF00000 - FFF45000: mapped SlabHeap FFF60000 - FFF8B000: mapped Kernel code FFFCC000 - FFFCD000: mapped IO I2C second bus (10144000 - 10145000) FFFCE000 - FFFCF000: mapped IO PDC (10400000 - 10401000) FFFD0000 - FFFD1000: mapped IO PDN (10141000 - 10142000) FFFD2000 - FFFD3000: mapped IO PXI (10163000 - 10164000) FFFD4000 - FFFD5000: mapped IO PAD (10146000 - 10147000) FFFD6000 - FFFD7000: mapped IO LCD (10202000 - 10203000) FFFD8000 - FFFD9000: mapped IO ? (10140000 - 10141000) FFFDA000 - FFFDB000: mapped IO XDMA (10200000 - 10201000) FFFDC000 - FFFE0000: mapped ? (1FFF8000 - 1FFFC000) FFFE1000 - FFFE2000: mapped ? (1FFF0000 - 1FFF1000) FFFE3000 - FFFE4000: mapped ? (1FFF2000 - 1FFF3000) FFFE5000 - FFFE9000: mapped L1 MMU table for VA xxx00000 FFFEA000 - FFFEB000: mapped ? (1FFF1000 - 1FFF2000) FFFEC000 - FFFED000: mapped ? (1FFF3000 - 1FFF4000) FFFEE000 - FFFF0000: mapped IO IRQ (17E00000 - 17E02000) FFFF0000 - FFFF1000: mapped Exception vectors FFFF2000 - FFFF6000: mapped L1 MMU table for VA xxx00000 FFFF7000 - FFFF8000: mapped ? (1FFF1000 - 1FFF2000) FFFF9000 - FFFFA000: mapped ? (1FFF3000 - 1FFF4000) FFFFB000 - FFFFE000: mapped L2 MMU tables (1FFF5000 - 1FFF8000)
0xFF4XX000
Each thread is allocated a 0x1000-byte page in this region: the first page at 0xFF401000 is for the first created thread, 0xFF403000 for the second thread. This region is used to store the SVC-mode stack for the thread, and thread context data used for context switching. When the IRQ handler, prefetch/data abort handlers, and undefined instruction handler are entered where the SPSR-mode=user, these handlers then store LR+SPSR for the current mode on the SVC-mode stack, then these handlers switch to SVC-mode.
This page does not contain a dedicated block for storing R0-PC(etc). For user-mode, the user-mode regs are instead saved on the SVC-mode stack when IRQs such as timers for context switching are triggered.
Structure of this page, relative to page_endaddr-0xC8:
| Offset | Size | Description |
|---|---|---|
| 0x0 | SVC-mode stack-top | |
| 0x18 | 0x28 | SVC-mode saved registers, stored/loaded during context switches: R4-R9, SL, FP, SP, LR. After loading these registers, the context switch code will jump to the loaded LR. |
| 0xC0 | 4 | fpexc from vmrs, used during context switches with the above saved registers. |
ARM11 User-land memory regions
NATIVE_FIRM/SAFE_MODE_FIRM Userland Memory
| Virtual Address Base | Physical Address Base | Region Max Size | Description |
|---|---|---|---|
| 0x00100000 / 0x14000000 | 0x03F00000 | The ExeFS:/.code is loaded here, executables must be loaded to the 0x00100000 region when the exheader "special memory" flag is clear. The 0x03F00000-byte size restriction only applies when this flag is clear. Executables are usually loaded to 0x14000000 when the exheader "special memory" flag is set, however this address can be arbitrary. | |
| 0x08000000 | For applications: FCRAM + GSP heap size | 0x08000000 | Heap mapped by ControlMemory |
| 0x10000000-StackSize | .bss physical address - total stack pages | StackSize from process exheader | Stack for the main-thread, initialized by the ARM11 kernel. The StackSize from the exheader is usually 0x4000, therefore the stack-bottom is usually 0x0FFFC000. The stack for the other threads is normally located in the process .data section however this can be arbitrary. |
| 0x10000000 | 0x04000000 | Shared memory | |
| 0x14000000 | FCRAM+0 | 0x08000000 | Can be mapped by ControlMemory, this is used for the application's GSP heap. |
| 0x1EC00000 | 0x10100000 | 0x01000000 | IO registers, the mapped IO pages which each process can access is specified in the CXI exheader.(Applications normally don't have access to registers in this range) |
| 0x1F000000 | 0x18000000 | 0x00600000 | VRAM, access to this is specified by the exheader. |
| 0x1FF00000 | 0x1FF00000 | 0x00080000 | DSP memory, access to this is specified by the exheader. |
| 0x1FF80000 | FCRAM memory page allocated by the ARM11 kernel. | 0x1000 | Configuration Memory, all processes have read-only access to this. |
| 0x1FF81000 | FCRAM memory page allocated by the ARM11 kernel. | 0x1000 | Shared page, all processes have read-access to this. Write access to this is specified by the exheader "Shared page writing" kernel flag. |
All executable pages are read-only, and data pages have the execute-never permission set. Normally .text from the loaded ExeFS:/.code is the only mapped executable memory. Executable CROs can be loaded into memory, once loaded the CRO .text section memory page permissions are changed via ControlProcessMemory from RW- to R-X. The address and size of each ExeFS:/.code section is stored in the exheader, the permissions for each section is: .text R-X, .rodata R--, .data RW-, and .bss RW-. The loaded .code is mapped to the addresses specified in the exheader by the ARM11 kernel. The stack permissions is initialized by the ARM11 kernel: RW-. The heap permissions is normally RW-.
All userland memory is mapped with RW permissions for privileged-mode. However, normally the ARM11 kernel only uses userland read/write instructions(or checks that the memory can be written from userland first) for accessing memory specified by SVCs.
The virtual memory located below 0x20000000 is process-unique, processes can't directly access memory for other processes. The virtual memory starting at 0x20000000 is only accessible in privileged-mode. When service commands are used, the kernel maps memory in the destination process for input/output buffers, where the addresses in the command received by the process is replaced by this mapped memory. When this is an input buffer, the buffer data is copied to the mapped memory. When this is an output buffer, the data stored in the mapped memory is copied to the destination buffer specified in the command.
The physical address which memory for the application memory-type is mapped to begins at FCRAM+0, the total memory allocated for this memory-type is stored in Configuration_Memory. Applications' .text + .rodata + .data under the application memory-type is mapped at FCRAM + APPMEMALLOC - (aligned page-size for .text + .rodata + .data). The application .bss is mapped at CODEADDR - .bss size aligned down to the page size.
TWL_FIRM Userland Memory
| Virtual Address Base | Physical Address Base | Size | Description |
|---|---|---|---|
| 0x00100000 | 0x1FFAB000 | 0x00055000 | Code + .(ro)data copied from the process 0x00300000 region is located here(.bss is located here as well). |
| 0x00155000 | 0x18555000 | 0x000AB000 | |
| 0x00200000 | 0x18500000 | 0x00100000 | |
| 0x00300000 | 0x24000000 | 0x04000000 | The beginning of the ARM11 process .text is located here. |
| 0x08000000 | 0x20000000 | 0x07E00000 | |
| 0x1EC00000 | 0x10100000 | 0x00400000 | IO |
| 0x1F000000 | 0x18000000 | 0x00600000 | VRAM |
| 0x1FF00000 | 0x1FF00000 | 0x00080000 | This is mapped to the DSP memory. |
The above regions are mapped by the ARM11 kernel. Later when the ARM11 process uses svcKernelSetState with type4, the kernel unmaps(?) the following regions: 0x00300000..0x04300000, 0x08000000..0x0FE00000, and 0x10000000..0xF8000000.
Detailed TWL_FIRM ARM11 Memory
| Process Virtual Address | Physical Address | Size | Description |
|---|---|---|---|
| 0x08000000 | 0x20000000 | 0x01000000*4 | DS(i) 0x02000000 RAM. Vaddr = (DSRAMOffset*4) + 0x08000000, where DSRAMOffset is DSRAMAddr-0x02000000. |
| 0x0FC00000 | 0x27C00000 | Loaded SRL binary, initially the dev DSi launcher SRL is located here(copied here by the ARM11 process). | |
| 0x0FD00000 | 0x27D00000 | The data located here is copied to here by the ARM11 process. The data located here is a TWL NAND bootloader image, using the same format+encryption/verification methods as the DSi NAND bootloader(stage2). The keyX for this bootloader keyslot is initially set to the retail DSi key-data, however when TWL_FIRM is launched this keyX key-data is replaced with a separate keyX. TWL_FIRM can use either the retail DSi bootloader RSA-1024 modulo, or a seperate modulo: normally only the latter is used(the former is only used when loading the image from FS instead of FCRAM). | |
| 0x0FDF7000 | 0x27DF7000 | 0x1000 | SRL header |
System memory details
0xFFFF9000 Pointer to the current KThread instance 0xFFFF9004 Pointer to the current KProcess instance 0xFFFF9010 Pointer a KThread (not sure what its role is)
Handles
The handle 0xFFFF8001 is a reference to the current KProcess.
IO Process/Kernel virtual addressing equivalence
It seems an IO register's process virtual address can be calculated by adding 0xEB00000 to its physical address.
VRAM Map While Running Webbrowser
- 0x1e6000-0x22C500 -- top screen framebuffer 0(240x400x3)
- 0x22C800-0x272D00 -- top screen framebuffer 1(240x400x3)
- 0x273000-0x2B9500 -- top screen framebuffer 2(240x400x3)
- 0x2B9800-0x2FFD00 -- top screen framebuffer 3(240x400x3)
- 0x48F000-0x4C7400 -- bottom screen framebuffer 0(240x320x3)
- 0x4C7800-0x4FF800 -- bottom screen framebuffer 1(240x320x3)