setup_ioapic_ids_from_mpc

#ifdef CONFIG_X86_32
/*
 * function to set the IO-APIC physical IDs based on the
 * values stored in the MPC table.
 *
 * by Matt Domsch <Matt_Domsch@dell.com>  Tue Dec 21 12:25:05 CST 1999
 */
void __init setup_ioapic_ids_from_mpc_nocheck(void)
{
    union IO_APIC_reg_00 reg_00;
    physid_mask_t phys_id_present_map;
    int ioapic_idx;
    int i;
    unsigned char old_id;
    unsigned long flags;
 
    /*
     * This is broken; anything with a real cpu count has to
     * circumvent this idiocy regardless.
     */
    apic->ioapic_phys_id_map(&phys_cpu_present_map, &phys_id_present_map);
 
    /*
     * Set the IOAPIC ID to the value stored in the MPC table.
     */
    for_each_ioapic(ioapic_idx) {
        /* Read the register 0 value */
        raw_spin_lock_irqsave(&ioapic_lock, flags);
        reg_00.raw = io_apic_read(ioapic_idx, 0);
        raw_spin_unlock_irqrestore(&ioapic_lock, flags);
 
        old_id = mpc_ioapic_id(ioapic_idx);
 
        if (mpc_ioapic_id(ioapic_idx) >= get_physical_broadcast()) {
            printk(KERN_ERR "BIOS bug, IO-APIC#%d ID is %d in the MPC table!...\n",
                ioapic_idx, mpc_ioapic_id(ioapic_idx));
            printk(KERN_ERR "... fixing up to %d. (tell your hw vendor)\n",
                reg_00.bits.ID);
            ioapics[ioapic_idx].mp_config.apicid = reg_00.bits.ID;
        }
 
        /*
         * Sanity check, is the ID really free? Every APIC in a
         * system must have a unique ID or we get lots of nice
         * 'stuck on smp_invalidate_needed IPI wait' messages.
         */
        if (apic->check_apicid_used(&phys_id_present_map,
                        mpc_ioapic_id(ioapic_idx))) {
            printk(KERN_ERR "BIOS bug, IO-APIC#%d ID %d is already used!...\n",
                ioapic_idx, mpc_ioapic_id(ioapic_idx));
            for (i = 0; i < get_physical_broadcast(); i++)
                if (!physid_isset(i, phys_id_present_map))
                    break;
            if (i >= get_physical_broadcast())
                panic("Max APIC ID exceeded!\n");
            printk(KERN_ERR "... fixing up to %d. (tell your hw vendor)\n",
                i);
            physid_set(i, phys_id_present_map);
            ioapics[ioapic_idx].mp_config.apicid = i;
        } else {
            physid_mask_t tmp;
            apic->apicid_to_cpu_present(mpc_ioapic_id(ioapic_idx),
                            &tmp);
            apic_printk(APIC_VERBOSE, "Setting %d in the "
                    "phys_id_present_map\n",
                    mpc_ioapic_id(ioapic_idx));
            physids_or(phys_id_present_map, phys_id_present_map, tmp);
        }
 
        /*
         * We need to adjust the IRQ routing table
         * if the ID changed.
         */
        if (old_id != mpc_ioapic_id(ioapic_idx))
            for (i = 0; i < mp_irq_entries; i++)
                if (mp_irqs[i].dstapic == old_id)
                    mp_irqs[i].dstapic
                        = mpc_ioapic_id(ioapic_idx);
 
        /*
         * Update the ID register according to the right value
         * from the MPC table if they are different.
         */
        if (mpc_ioapic_id(ioapic_idx) == reg_00.bits.ID)
            continue;
 
        apic_printk(APIC_VERBOSE, KERN_INFO
            "...changing IO-APIC physical APIC ID to %d ...",
            mpc_ioapic_id(ioapic_idx));
 
        reg_00.bits.ID = mpc_ioapic_id(ioapic_idx);
        raw_spin_lock_irqsave(&ioapic_lock, flags);
        io_apic_write(ioapic_idx, 0, reg_00.raw);
        raw_spin_unlock_irqrestore(&ioapic_lock, flags);
 
        /*
         * Sanity check
         */
        raw_spin_lock_irqsave(&ioapic_lock, flags);
        reg_00.raw = io_apic_read(ioapic_idx, 0);
        raw_spin_unlock_irqrestore(&ioapic_lock, flags);
        if (reg_00.bits.ID != mpc_ioapic_id(ioapic_idx))
            pr_cont("could not set ID!\n");
        else
            apic_printk(APIC_VERBOSE, " ok.\n");
    }
}
函数源码
