NPDM
This is the Switch equivalent of 3DS exheader. This is the file with extension ".npdm" in {Switch ExeFS}. The size of this file varies.
| Offset | Size | Description |
|---|---|---|
| 0x0 | 0x80 | META |
| 0x80 | <Varies> | ACID |
| <See META> | <See META> | ACI0 |
META
| Offset | Size | Description |
|---|---|---|
| 0x0 | 0x4 | Magic "META". |
| 0xE | 1 | |
| 0xF | 1 | |
| 0x1C | 4 | |
| 0x20 | ? | Title name |
| 0x70 | 0x4 | #ACI0 offset |
| 0x74 | 0x4 | #ACI0 size |
| 0x78 | 0x4 | #ACID offset |
| 0x7C | 0x4 | #ACID size |
ACID
| Offset | Size | Description |
|---|---|---|
| 0 | 0x100 | RSA-2048 signature, seems to verify the data starting at 0x100 with the size field from 0x204. |
| 0x100 | 0x100 | RSA-2048 public key, seems to be used for the second NCA signature. |
| 0x200 | 0x4 | Magic "ACID". |
| 0x204 | 0x4 | s32 Size field used with the above signature(?). |
| 0x208 | 0x4 | Zeroes |
| 0x20C | 0x4 | Retail flag. Must be 1 on retail, on devunit 0 is also allowed. |
| 0x210 | 0x8 | Title id |
| 0x218 | 0x8 | Title id again |
| 0x220 | 0x4 | #FS Access Control offset |
| 0x224 | 0x4 | #FS Access Control size |
| 0x228 | 0x4 | #Service Access Control offset |
| 0x22C | 0x4 | #Service Access Control size |
| 0x230 | 4 | #Kernel Access Control offset |
| 0x234 | 4 | #Kernel Access Control size |
| 0x238 | 0x8 | Padding |
ACI0
Looks like an old crappy version of ACID. It has the guessed version field 0 instead of 1.
FS Access Control
| Word | Bit | Description |
|---|---|---|
| 0 | Version? Always 1. | |
| 1 | 0 | MountContent* is accessible when set. |
| 1 | 2 | Enables access to Bis partitionID 27 and 28? |
Web-applets access control:
- "LibAppletWeb" and "LibAppletOff" have same access control: word0 bit0 set, word1 bit0 and bit3 set, and word2 bit30 set.
- Rest of the web-applets: Same as above except word1 bit0 isn't set.
Service Access Control
This is a list of service-name strings which the title has access to, with the following structure:
+0: control_byte
+1: {service-name without nul-terminator}
Bitmask 0x0F in control_byte is the {length of the service-name without nul-terminator} - 1.
Bitmask 0x80 in control_byte means service is allowed to be registered.
The service string can contain a wildcard * character.
Kernel Access Control
On Switch, descriptors are identified by pattern 01..11 in low bits.
| Pattern of lower bits | Type | Fields |
|---|---|---|
0bxxxxxxxxxxxx0111
|
Kernel flags | Bit31-24: Highest allowed cpu id, bit23-16: Lowest allowed cpu id, bit15-10: Highest allowed thread prio, bit9-4: Lowest allowed thread prio |
0bxxxxxxxxxxx01111
|
Syscall mask | Bits 29-31: Syscall mask table index; Bits 5-28: Mask |
0bxxxxxxxxxx011111
|
? | Unknown. Requires two consecutive pairs of this descriptor type. |
0bxxxxxxxxx0111111
|
Map IO page (RW) | Bits 7-31: Page |
0bxxxxxxxx01111111
|
Map IO range | Bits 7-30: Alternating start page and number of pages, bit31: Alternating read-only flag then MemoryAttribute 0x2001/0x42002 selector flag |
0bxxxx011111111111
|
Interrupt pair | Bits 12-21: Irq0, bits 20-31: Irq1, 0x3FF means empty. |
0xxxx0111111111111
|
||
0xxx01111111111111
|
||
0xx011111111111111
|
||
0x0111111111111111
|
||
| All ones | Ignored |