pussuw commented on a change in pull request #5782: URL: https://github.com/apache/incubator-nuttx/pull/5782#discussion_r837845396
########## File path: arch/risc-v/src/common/supervisor/riscv_context.S ########## @@ -0,0 +1,234 @@ +/**************************************************************************** + * arch/risc-v/src/common/supervisor/riscv_context.S + * + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. The + * ASF licenses this file to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance with the + * License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT + * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the + * License for the specific language governing permissions and limitations + * under the License. + * + ****************************************************************************/ + +.file "riscv_context.S" + +/**************************************************************************** + * Included Files + ****************************************************************************/ + +#include <nuttx/config.h> +#include <arch/mode.h> + +#include "riscv_exception_macros.S" + +/**************************************************************************** + * Pre-processor Definitions + ****************************************************************************/ + +/**************************************************************************** + * Public Symbols + ****************************************************************************/ + + .globl riscv_saveusercontext + .globl riscv_fullcontextrestore + .globl riscv_switchcontext + .globl riscv_syscall_return + +/**************************************************************************** + * Name: riscv_saveusercontext + * + * Description: + * Save user context, partially destroys the caller's context + * + * C Function Prototype: + * int riscv_saveusercontext(uintptr_t *saveregs); + * + * Input Parameters: + * saveregs - Context to save + * + * Returned Value: + * 0 on context switch + * 1 on no context switch + * + * Assumptions: + * Global interrupts disabled by the caller. + * + ****************************************************************************/ + +.type riscv_saveusercontext, function + +riscv_saveusercontext: Review comment: I agree that this brings more code to maintain, which is bad. My disagreement is fundamental / philosophical. A context switch is just swapping registers. Performing a syscall using the trap handler to do this was a bit awkward to me. Yes, it saves code lines, but it makes it slower and more complex. But to get things moving forward I'll remove these asm functions and use the macros that use sys_callx instead. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: commits-unsubscr...@nuttx.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
