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author | Robert Morris <[email protected]> | 2010-08-05 21:16:55 -0400 |
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committer | Robert Morris <[email protected]> | 2010-08-05 21:16:55 -0400 |
commit | 1afc9d3fcaa7c5992659bb8b69f639b746dda2bc (patch) | |
tree | e60a41707282ba0ef2c1e00b9cba97bb71339284 /main.c | |
parent | c99599784e950169d85bf1e4446e7dbfb1a40f59 (diff) | |
download | xv6-labs-1afc9d3fcaa7c5992659bb8b69f639b746dda2bc.tar.gz xv6-labs-1afc9d3fcaa7c5992659bb8b69f639b746dda2bc.tar.bz2 xv6-labs-1afc9d3fcaa7c5992659bb8b69f639b746dda2bc.zip |
add some comments
find out the hard way why user and kernel must have separate segment descriptors
Diffstat (limited to 'main.c')
-rw-r--r-- | main.c | 22 |
1 files changed, 12 insertions, 10 deletions
@@ -16,13 +16,13 @@ main(void) { mpinit(); // collect info about this machine lapicinit(mpbcpu()); - ksegment(); + ksegment(); // set up segments picinit(); // interrupt controller ioapicinit(); // another interrupt controller consoleinit(); // I/O devices & their interrupts uartinit(); // serial port - pminit(); // physical memory for kernel - jkstack(); // Jump to mainc on a properly-allocated stack + pminit(); // discover how much memory there is + jkstack(); // call mainc() on a properly-allocated stack } void @@ -41,7 +41,7 @@ void mainc(void) { cprintf("\ncpu%d: starting xv6\n\n", cpu->id); - kvmalloc(); // allocate the kernel page table + kvmalloc(); // initialze the kernel page table pinit(); // process table tvinit(); // trap vectors binit(); // buffer cache @@ -57,8 +57,9 @@ mainc(void) mpmain(); } -// Bootstrap processor gets here after setting up the hardware. -// Additional processors start here. +// Common CPU setup code. +// Bootstrap CPU comes here from mainc(). +// Other CPUs jump here from bootother.S. static void mpmain(void) { @@ -66,11 +67,11 @@ mpmain(void) ksegment(); lapicinit(cpunum()); } - vminit(); // Run with paging on each processor + vminit(); // turn on paging cprintf("cpu%d: starting\n", cpu->id); - idtinit(); + idtinit(); // load idt register xchg(&cpu->booted, 1); - scheduler(); + scheduler(); // start running processes } static void @@ -85,6 +86,7 @@ bootothers(void) // placed the start of bootother.S there. code = (uchar *) 0x7000; memmove(code, _binary_bootother_start, (uint)_binary_bootother_size); + for(c = cpus; c < cpus+ncpu; c++){ if(c == cpus+cpunum()) // We've started already. continue; @@ -95,7 +97,7 @@ bootothers(void) *(void**)(code-8) = mpmain; lapicstartap(c->id, (uint)code); - // Wait for cpu to get through bootstrap. + // Wait for cpu to finish mpmain() while(c->booted == 0) ; } |