source: trunk/user/init/init.c @ 588

Last change on this file since 588 was 588, checked in by alain, 4 years ago

Introduce a signal based synchro between INIT and KSH processes
to sequencialize multiple KSH[i] processes creation.

File size: 6.2 KB
Line 
1///////////////////////////////////////////////////////////////////////////////////////
2// File   :  init.c
3// Date   :  January 2018
4// Author :  Alain Greiner
5///////////////////////////////////////////////////////////////////////////////////////
6// This single thread application implement the "init" process for ALMOS-MKH.
7// It uses the fork/exec syscalls to create N KSH child processes
8// (one child process per user terminal).
9// Then calls the wait() function to block, and reactivate any child KSH process
10// that has been deleted, using a new fork/exec.
11// It includes the hard_config.h file to get th NB_TXT_CHANNELS parameter.
12///////////////////////////////////////////////////////////////////////////////////////
13
14#include <hard_config.h>
15#include <unistd.h>
16#include <stdlib.h>
17#include <stdio.h>
18#include <pthread.h>
19#include <almosmkh.h>
20#include <hal_macros.h>
21#include <sys/wait.h>
22
23#define DEBUG_PROCESS_INIT    0
24
25// TODO improve the get_config() syscall to return nb_txt_channels
26// and avoid the hard_config include [AG]
27
28// TODO introduce a communication channel between INIT and KSH
29// to allow KSH to signal INIT the exec completion.
30
31////////////////
32int main( void )
33{
34    int           i;
35    int           ret_fork;      // fork return value 
36    int           ret_exec;      // exec return value 
37    int           rcv_pid;       // pid received from the wait syscall
38    int           status;        // used by the wait syscall
39    char          string[64];    // log messages on kernel TXT0
40
41#if DEBUG_PROCESS_INIT
42display_string("[INIT] process enters");
43#endif
44
45    // check number of TXT channels
46    if( NB_TXT_CHANNELS < 2 )
47    {
48        printf("\n[ERROR] in init process : number of TXT channels must be larger than 1\n");
49        exit( EXIT_FAILURE );
50    }
51
52    // create the KSH processes (one per user terminal)
53    for( i = 1 ; i <  NB_TXT_CHANNELS ; i++ )
54    {
55        // INIT process fork process CHILD[i]
56        ret_fork = fork();
57
58        if( ret_fork < 0 )   // error in fork
59        {
60            // INIT display error message 
61            snprintf( string , 64 , "[INIT ERROR] cannot fork child[%d] => suicide" , i );
62            display_string( string );
63
64            // INIT suicide
65            exit( 0 );
66        }
67        else if( ret_fork == 0 )                    // we are in CHILD[i] process
68        {
69            // CHILD[i] process exec process KSH[i]
70            ret_exec = execve( "/bin/user/ksh.elf" , NULL , NULL ); 
71
72            if ( ret_exec )   // error in exec             
73            {
74                // CHILD[i] display error message
75                snprintf( string , 64 , 
76                "[INIT ERROR] CHILD[%d] cannot exec KSH / ret_exec = %d" , i , ret_exec );
77                display_string( string );
78            }
79        }
80        else                                      // we are in INIT process
81        {
82            // INIT display CHILD[i] process PID
83            snprintf( string , 64 , "[INIT] created KSH[%d] / pid = %x", i , ret_fork ); 
84            display_string( string );
85
86            // wait signal from KSH[i]
87            pause();
88        }
89    } 
90 
91#if DEBUG_PROCESS_INIT
92{
93    unsigned int  x_size;        // number of clusters in a row
94    unsigned int  y_size;        // number of clusters in a column
95    unsigned int  ncores;        // number of cores per cluster
96    unsigned int  x;             // cluster x coordinate
97    unsigned int  y;             // cluster y coordinate
98    unsigned int  cxy;           // cluster identifier
99    unsigned int  lid;           // core local index
100
101    // get hardware config
102    get_config( &x_size , &y_size , &ncores );
103
104    // INIT displays processes and threads in all clusters
105    for( x = 0 ; x < x_size ; x++ )
106    {
107        for( y = 0 ; y < y_size ; y++ )
108        {
109            cxy = HAL_CXY_FROM_XY( x , y );
110            display_cluster_processes( cxy );
111            for( lid = 0 ; lid < ncores ; lid++ )
112            { 
113                display_sched( cxy , lid );
114            }
115        }
116    }
117}
118#endif
119
120    // This loop detects the termination of the KSH[i] processes,
121    // and recreate a new KSH[i] process when required.
122    while( 1 )
123    {
124        // block on child processes termination
125        rcv_pid = wait( &status );
126
127        if( WIFSTOPPED( status ) )                         // stopped => unblock it
128        {
129            // display string to report unexpected KSH process block
130            snprintf( string , 64 , "[INIT] KSH process %x stopped => unblock it" , rcv_pid );
131            display_string( string ); 
132
133            // TODO : unblock KSH [AG]
134
135        }  // end KSH stopped handling
136
137        if( WIFSIGNALED( status ) || WIFEXITED( status ) )  // killed => recreate it
138        {
139            // display string to report KSH process termination
140            snprintf( string , 64 , "[INIT] KSH process %x terminated => recreate", rcv_pid );
141            display_string( string ); 
142
143            // INIT process fork a new CHILD process
144            ret_fork = fork();
145
146            if( ret_fork < 0 )                          // error in fork
147            {
148                // INIT display error message
149                snprintf( string , 64 , "[INIT ERROR] cannot fork child => suicide");
150                display_string( string );
151
152                // INIT suicide
153                exit( 0 );
154            }
155            else if( ret_fork == 0 )                    // we are in CHILD process
156            {
157                // CHILD process exec process KSH
158                ret_exec = execve( "/bin/user/ksh.elf" , NULL , NULL ); 
159
160                if ( ret_exec )   // error in exec             
161                {
162                    // CHILD display error message on TXT0 terminal
163                    snprintf( string , 64 , "[INIT ERROR] CHILD cannot exec KSH" );
164                    display_string( string );
165                }
166            }
167            else                                       // we are in INIT process
168            {
169                // INIT display new KSH process PID
170                snprintf( string , 64 , "[INIT] re-created KSH / pid = %x", ret_fork ); 
171                display_string( string );
172            }
173        } // end KSH kill handling
174
175    }  // end while waiting KSH[i] termination
176
177} // end main()
178
Note: See TracBrowser for help on using the repository browser.