From dbae68b7e86e7eefe2efae15139f398173fb9cda Mon Sep 17 00:00:00 2001 From: Natalie Agus Date: Mon, 15 Apr 2024 12:03:45 +0800 Subject: [PATCH] style: bold SVC --- docs/Software/o_virtualmachine.md | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/docs/Software/o_virtualmachine.md b/docs/Software/o_virtualmachine.md index cf03b7a..f7a4e33 100644 --- a/docs/Software/o_virtualmachine.md +++ b/docs/Software/o_virtualmachine.md @@ -351,10 +351,10 @@ During this event, * The illop handler will look at `Reg[R0]` and invoke the right service routine to provide the requested service. * Upon returning, the service routine will put its return the result in `Reg[R0]`. * The illop handler resumes the execution of the originating process: - * `Reg[XP] = Reg[XP] -4` * `JMP[XP]` - +{:.note} +There's no need to do `Reg[XP] = Reg[XP]-4` because we don't wish to re-invoke the Trap / SVC when we return to the calling process. One common scenario where a process running in user mode needs the Kernel service is when it asks for keyboard / mouse input, for example: