How does preprocessor resolve the path of linux kernel' head file?

By -

I am new to C programming language, and currently trying to add new syscall to Linux kernel by re-compiling the kernel.

When I read the source code, I found it very difficult to locate the path of head file.

For example:

#include <linux/kernel.h>   /* for printk */
#include <linux/syscalls.h> /* for SYSCALL_DEFINE1 macro */

SYSCALL_DEFINE1(printmsg, int, i)
{
    printk(KERN_DEBUG "Hello! This is a msg %d", i);
    return 1;
}

This is one of my customized system calls. I edited the MakeFile in kernel/ folder and syscall_64.tbl . After re-compiling, it worked. No compiling error.

However, my problem now is how the preprocessor resolves the path like <linux/syscalls.h>. Based on my previous understanding, the preprocessor would go to the folder /usr/include for searching. Certainly, there is no linux/syscalls.h within /usr/include.

I found linux/syscalls.h is actually in linux's project include/linux/ .

I was wondering what makes the preprocessor search within the project just like include " " when it is actually using <>.

I was wondering if it is because of some part of MakeFile? If so, which command in MakeFile could make this happen?

Thank you for any help, and please let me know if I misunderstood something.



Comments

Post a Comment

Popular posts from this blog

Today Walkin 14th-Sept

By -
Image
14th Sept 2017 ( GO Through all List) Read Walkin details properly , Try to call company before attending if possible !!! ==================================== 1. Myntra through fresherworld (Call Based , Venue shared to shortlisted candidates) _____________________________ 2. Magna : Hiring for Client Harman : C++
Read more

Hibernate Search - Elasticsearch with JSON manipulation

By -
Elasticsearch with JSON manipulation Elasticsearch ships with many features. It is possible that at some point, one feature you need will not be exposed by the Search DSL. To work around such limitations, Hibernate Search provides ways to: Transform the HTTP request sent to Elasticsearch for search queries. Read the raw JSON of the HTTP response received from Elasticsearch for search queries. Direct changes to the HTTP request may conflict with Hibernate Search features and be supported differently by different versions of Elasticsearch. Similarly, the content of the HTTP response may change depending on the version of Elasticsearch, depending on which Hibernate Search features are used, and even depending on how Hibernate Search features are implemented. Thus, features relying on direct access to HTTP requests or responses cannot be guaranteed to continue to work when upgrading Hibernate Search, even for micro upgrades (x.y.z to x.y.(z+1)). Use this at your own risk.
Read more

Spring Elasticsearch Operations

By -
Elasticsearch Operations Spring Data Elasticsearch uses two interfaces to define the operations that can be called against an Elasticsearch index. These are ElasticsearchOperations and ReactiveElasticsearchOperations. Whereas the first is used with the classic synchronous implementations, the second one uses reactive infrastructure. The default implementations of the interfaces offer: Read/Write mapping support for domain types. A rich query and criteria api. Resource management and Exception translation. ElasticsearchTemplate The ElasticsearchTemplate is an implementation of the ElasticsearchOperations interface using the Transport Client. @Configuration public class TransportClientConfig extends ElasticsearchConfigurationSupport {   @Bean   public Client elasticsearchClient() throws UnknownHostException {                      Settings settings = Settings.builder().put("cluster.name", "elasticsearch").build();     TransportClient client = new P
Read more