Difference between revisions of "NPDM"

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Revision as of 04:16, 3 July 2017

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".
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
0x100 0x100 RSA-2048 public key
0x200 0x4 Magic "ACID".
0x204 0x8 Zeroes
0x20C 0x4 Format version? (1)
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.
0 3 This is only bit set for ShopN in the permissions-u32.
1 2 Enables access to Bis partitionID 27 and 28?

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 bits 15-0 Type Fields
0bxxxxxxxxxxxx0111 Kernel flags 5-0: Main thread priority?
0bxxxxxxxxxxx01111 Syscall mask Bits 29-31: Syscall mask table index; Bits 5-28: mask
0bxxxxxxxxx0111111 Map IO page Bits 7-31: page
0bxxxxxxxx01111111 Map IO range Bits 7-31: page then size alternating
0bxxxx011111111111 Interrupt pair Bits 12-21: irq0, bits 20-31: irq1, 0x3FF means empty.