Starting 2nd processor on Dual P3 system

Starting 2nd processor on Dual P3 system

Post by Bill Sakod » Fri, 03 Aug 2001 00:04:29

Lynx OS runs only single processors.  Under Lynx, I am trying to start
the second processor on a Dual P3 system to run as co-processor.  The
second processor will have little interaction with the main system, so I
believe the main challenge is getting the processor started.

According to Intel documentation, the running processor should send a
Start IPI via APIC.  I have tried this, but there are no signs of
processor 2 starting. I am trying to vector it to 0x1000 physical, where
there is a jump-to-yourself instruction planted.  I hope to find
processor 2 looping there.

In Linux 2.4.5 smpboot.c, the Start IPI is used only as a secondary
method of startup.  The primary method twiddles some stuff in the CMOS
and low memory, which I do not understand; then raises and lowers INIT.
Can someone explain what the first few lines - CMOS_WRITE and setting
phys 0x469 and 0x467 are doing?  Is this standard BIOS stuff, or is it

Any other suggestions on processor startup appreciated.

Thanks - Bill Sakoda

/*   From smpboot.c; */

 CMOS_WRITE(0xa, 0xf);
 *((volatile unsigned short *) phys_to_virt(0x469)) = start_eip >> 4;
 *((volatile unsigned short *) phys_to_virt(0x467)) = start_eip & 0xf;

  * Be paranoid about clearing APIC errors.
 if (APIC_INTEGRATED(apic_version[apicid])) {
  apic_write(APIC_ESR, 0);

  * Status is now clean
 send_status = 0;
 accept_status = 0;
 boot_status = 0;

  * Starting actual IPI sequence...

 Dprintk("Asserting INIT.\n");

  * Turn INIT on target chip
 apic_write_around(APIC_ICR2, SET_APIC_DEST_FIELD(apicid));

  * Send IPI
    | APIC_DM_INIT);

 Dprintk("Waiting for send to finish...\n");


1. SMP: dual P3 system not booting

I have a system with two P3 (1GHz each) and 2GB RAM.

I installed Red Hat Linux 7.1 off the CDs, but the SMP kernel does not boot.  
The boot process gets through the following before halting:

Total of 2 processors activated (4010.80 Bogo MIPS).
Before bogocount -  setting activated=1.
Boot done.
...Changing IO_APIC physical APIC ID to 2... ok.
Synchronizing Arb IDs.
...TIMER: vector=49 pin1=2 pin2=0
<stops here>

Does anyone know what I need to do to get the SMP kernel working?


 ~ Bob

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