ARM Architecture Reference Manual ARMv7-A and ARMv7-R edition

Instruction Details
A8.6.217 SUBS PC, LR and related instructions
These instructions are for system level use only. See SUBS PC, LR and related instructions on page B6-25.
A8.6.218 SVC (previously SWI)
Supervisor Call, previously called a Software Interrupt. For more information, see Exceptions on
page B1-30, and in particular Supervisor Call (SVC) exception on page B1-52.
You can use this instruction as a call to an operating system to provide a service.
Encoding T1 ARMv4T, ARMv5T*, ARMv6*, ARMv7
SVC #
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
1 1 0 1 1 1 1 1 imm8
imm32 = ZeroExtend(imm8, 32);
// imm32 is for assembly/disassembly, and is ignored by hardware. SVC handlers in some
// systems interpret imm8 in software, for example to determine the required service.
Encoding A1 ARMv4*, ARMv5T*, ARMv6*, ARMv7
SVC #
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
cond 1 1 1 1 imm24
imm32 = ZeroExtend(imm24, 32);
// imm32 is for assembly/disassembly, and is ignored by hardware. SVC handlers in some
// systems interpret imm24 in software, for example to determine the required service.
A8-430 Copyright © 1996-1998, 2000, 2004-2008 ARM Limited. All rights reserved. ARM DDI 0406B