diff options
| -rw-r--r-- | kernel/entry.S | 18 | ||||
| -rw-r--r-- | user/init.c | 16 | ||||
| -rw-r--r-- | user/initcode.S | 2 |
3 files changed, 21 insertions, 15 deletions
diff --git a/kernel/entry.S b/kernel/entry.S index 62fe1f2..b72ddbc 100644 --- a/kernel/entry.S +++ b/kernel/entry.S @@ -1,14 +1,8 @@ - # qemu -kernel starts at 0x1000. the instructions - # there seem to be provided by qemu, as if it - # were a ROM. the code at 0x1000 jumps to - # 0x80000000, the _start function here, - # in machine mode. each CPU starts here. -.section .data -.globl stack0 + # qemu -kernel loads the kernel at 0x80000000 + # and causes each CPU to jump there. + # kernel.ld causes the following code to + # be placed at 0x80000000. .section .text -.globl start -.section .text -.globl _entry _entry: # set up a stack for C. # stack0 is declared in start.c, @@ -22,5 +16,5 @@ _entry: add sp, sp, a0 # jump to start() in start.c call start -junk: - j junk +spin: + j spin diff --git a/user/init.c b/user/init.c index 5df6deb..13764ca 100644 --- a/user/init.c +++ b/user/init.c @@ -31,8 +31,20 @@ main(void) printf("init: exec sh failed\n"); exit(1); } - while((wpid=wait(0)) >= 0 && wpid != pid){ - //printf("zombie!\n"); + + for(;;){ + // this call to wait() returns if the shell exits, + // or if a parentless process exits. + wpid = wait((int *) 0); + if(wpid == pid){ + // the shell exited; restart it. + break; + } else if(wpid < 0){ + printf("init: wait returned an error\n"); + exit(1); + } else { + // it was a parentless process; do nothing. + } } } } diff --git a/user/initcode.S b/user/initcode.S index ca76972..e8f7a91 100644 --- a/user/initcode.S +++ b/user/initcode.S @@ -1,4 +1,4 @@ -# Initial process execs /init. +# Initial process that execs /init. # This code runs in user space. #include "syscall.h" |