On 04/16/2012 09:20 AM, Onkar N Mahajan wrote:
> On Mon, 2012-04-16 at 12:13 -0700, Randy Dunlap wrote:
>> On 04/16/2012 09:02 AM, Onkar N Mahajan wrote:
>>
>>> Hello list,
>>>
>>> I am trying to understand the PCI functionality in Linux kernel.
>>> What is the best way to start to understanding this - where to start
>>> in the kernel code ? Books ? Manuals ?
>>>
>>> I started reading the code - where I am stuck in this function -
>>> pci_check_type2() ; Wherein I am not able to get from where these values
>>> 0xCFB,0xCF8,0xCFA are arrived at ? I guess these are port numbers , but
>>> in which manuals can I find this all information.
>>>
>>> linux/arch/x86/pci/init.c:
>>> static int __init pci_check_type2(void)
>>> {
>>> unsigned long flags;
>>> int works = 0;
>>>
>>> local_irq_save(flags);
>>>
>>> outb(0x00, 0xCFB);
>>> outb(0x00, 0xCF8);
>>> outb(0x00, 0xCFA);
>>> if (inb(0xCF8) == 0x00 && inb(0xCFA) == 0x00 &&
>>> pci_sanity_check(&pci_direct_conf2)) {
>>> works = 1;
>>> }
>>>
>>> local_irq_restore(flags);
>>>
>>> return works;
>>> }
>>>
>>>
>>> Please help me figuring out right manuals for this.
>>
>>
>> The PCI spec (version 2.1 seems to be all I have available)
>> discusses PCI Configuration Mechanisms and Special Cycles and
>> these PCI config registers.
>>
> Thanks Randy , for your help. Can you please also guide me with
> respect to good way to start understanding the PCI implementation
> in Linux ?
Not really. It's best to ask specific questions about it.
--
~Randy
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