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releases:3.2.0:developersguide:newkernelcall [2014/11/11 08:52] (current)
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 +====== Adding a new Kernel Call in MINIX ======
 +
 +//(Working Draft)//
 +
 +This tutorial helps you to add a new kernel call in MINIX. Let's say your new kernel call is called //sample//.
 +
 +  - Add the prototype of your kernel function do_sample() in the file: ///​usr/​src/​kernel/​system.h// ​
 +<​code>​
 +...
 +int do_sample(struct proc *caller, message *m_ptr);
 +
 +#​endif ​ /* SYSTEM_H */
 +</​code>​
 +  - Write the implementation of do_sample() in its own source file: ///​usr/​src/​kernel/​system/​do_sample.c// ​
 +<​code>​
 +#include "​kernel/​system.h"​
 +#include <​minix/​endpoint.h>​
 +
 +/​*===========================================================================*
 +  *                                do_sample ​                                 *
 +  *===========================================================================*/​
 +int do_sample(struct proc *caller_ptr,​ message *m_ptr)
 +{
 +        return(OK);
 +}
 +</​code>​
 +  - Add do_sample.c to the Makefile for compilation:​ ///​usr/​src/​kernel/​system/​Makefile.inc// ​
 +<​code>​
 +# Makefile for system library implementation
 +.include <​bsd.own.mk>​
 +
 +.PATH: ​ ${.CURDIR}/​system
 +SRCS+= ​ \
 +        do_fork.c \
 +        do_exec.c \
 +...
 +
 +        do_statectl.c \
 +        do_sample.c
 +</​code>​
 +  - Map SYS_SAMPLE to do_sample() in the system call table: ///​usr/​src/​kernel/​system.c// ​
 +<​code>​
 +...
 +  map(SYS_STATECTL,​ do_statectl); ​      /* let a process control its state */
 +  map(SYS_SAMPLE,​ do_sample); ​          /* your kernel call */
 +...
 +</​code>​
 +  - Add a prototype for the sys_sample function in the file: ///​usr/​src/​common/​include/​minix/​syslib.h// ​
 +<​code>​
 +...
 +int sys_sample(unsigned flags, endpoint_t proc_ep);
 +...
 +</​code>​
 +  - Add the call number for sys_sample to the call vector and increment its dimension: ///​usr/​src/​common/​include/​minix/​com.h// ​
 +<​code>​
 +...
 +#  define SYS_STATECTL (KERNEL_CALL + 55)       /* sys_statectl() */
 +#  define SYS_SAMPLE ​   (KERNEL_CALL + 56)      /* sys_sample() */
 +
 +
 +/* Total */
 +#define NR_SYS_CALLS ​   57      /* number of kernel calls */
 +...
 +</​code>​
 +  - Add the SAMPLE service to the system tab: ///​usr/​src/​commands/​service/​service.c//;​ build the updated system tab and install it with //make; make install// from ///​usr/​src/​commands/​service/// ​
 +<​code>​
 +...
 +struct
 +{
 +        char *label;
 +        int call_nr;
 +} system_tab[]=
 +{
 +...
 +        { "​SAMPLE", ​            ​SYS_SAMPLE },
 +        { NULL,         0 }
 +};
 +...
 +</​code>​
 +  - Write your implementation of the function sys_sample in a new file: ///​usr/​src/​lib/​libsys/​sys_sample.c// ​
 +<​code>​
 +#include "​syslib.h"​
 +
 +int sys_sample(unsigned flags, endpoint_t proc_ep)
 +{
 +        message m;
 +
 +        return(_kernel_call(SYS_SAMPLE,​ &m));
 +}
 +</​code>​
 +  - Add sys_sample.c to the Makefile, and install it in ///​usr/​lib/​${MACHINE_ARCH}//​ with //make install//​. ​
 +<​code>​
 +# Makefile for libsys
 +
 +LIB=            sys
 +
 +SRCS=  \
 +...
 +        sys_sample.c \
 +...
 +</​code>​
 +  - Test the new kernel call with a [[.:​driverprogramming|hello driver]] in ///​usr/​src/​drivers/​sample_test//​.
 +  - Rebuild the kernel and install it with //make; make install// from ///​usr/​src/​tools//​.
  
releases/3.2.0/developersguide/newkernelcall.txt · Last modified: 2014/11/11 08:52 (external edit)