xiaoxiang781216 commented on a change in pull request #3170: URL: https://github.com/apache/incubator-nuttx/pull/3170#discussion_r604580125
########## File path: include/nuttx/lib/libvars.h ########## @@ -0,0 +1,76 @@ +/**************************************************************************** + * include/nuttx/lib/libvars.h + * + * 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. + * + ****************************************************************************/ + +#ifndef __INCLUDE_NUTTX_LIB_LIBVARS_H +#define __INCLUDE_NUTTX_LIB_LIBVARS_H + +/**************************************************************************** + * Included Files + ****************************************************************************/ + +#include <nuttx/config.h> + +#include <stdbool.h> + +#include <nuttx/lib/getopt.h> + +/**************************************************************************** + * Public Types + ****************************************************************************/ + +#ifndef CONFIG_BUILD_KERNEL +/* This structure encapsulates all task-specific variables needed by the C + * Library. This structure is retained at the beginning of the main thread + * of and is accessed via a reference stored in the TLS of all threads in + * the task group. + * + * NOTE: task-specific variables are not needed in the KERNEL build. Included + * that build mode, all global variables are inherently process-specific. + */ + +struct libvars_s +{ + struct getopt_s lv_getopt; /* Globals used by getopt() */ +}; +#endif Review comment: > > Maybe we can add options to compile out functions such as getopt() when not used, which would remove the relevant globals from the stack. > > Possibly, but there are too many configuration options now. getopt() requires only 24 bytes of storage. Hardly worth the added complexity. Yes, each allocation has more cost than stack variables(min 16 bytes quantity, fragmentation and time for alloc/free). So it's better to embed small global variables like getopt used directly into stack. -- 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. For queries about this service, please contact Infrastructure at: [email protected]
