Re: PATCH: Support PCI device sorting (Re: PCI device order problem)

[Jeff Garzik <jgarzik@pobox.com>]

H. J. Lu wrote:

>On Sat, Oct 26, 2002 at 05:34:57PM -0400, Jeff Garzik wrote:
>  
>
>>H. J. Lu wrote:
>>
>>    
>>
>>>On Sat, Oct 26, 2002 at 05:12:51PM -0400, Jeff Garzik wrote:
>>> 
>>>
>>>      
>>>
>>>>Well, WRT your implementation, the function you add is dead code if your 
>>>>new config variable is not set, which is not desireable at all.
>>>>   
>>>>
>>>>        
>>>>
>>>I am not sure if I understand what you were trying to say. If
>>>CONFIG_PCI_SORT_BY_BUS_SLOT_FUNC is not set, you should be able to 
>>>pass "pci=bussort" to kernel to sort the PCI device by bus, slot and
>>>function. Did I miss something?
>>> 
>>>
>>>      
>>>
>>The sorting function you add should be covered by the ifdef you add.
>>    
>>
>
>Have you tried? If I did that, the kernel wouldn't even compile. As I
>said, when CONFIG_PCI_SORT_BY_BUS_SLOT_FUNC isn't defined, my sorting
>function is still available, just not called by default.
>
Which is the entire problem.  The kernel compiles and builds just fine 
right now, without your function.

If it is "just not called by default" then it clearly can be removed at 
compile time when a certain CONFIG_xxx is not defined.


>>>>WRT the overall idea, I would prefer to see what Linus and Martin Mares 
>>>>(and Ivan K) thought about it, before merging it.  The x86 PCI code is 
>>>>very touchy, and your patch has the potential to change driver probe 
>>>>order for little gain.
>>>>
>>>>        
>>>>
>>>The whole purpose of my patch is to change PCI driver probe order in
>>>such a way that is BIOS independent.
>>>
>>>      
>>>
>>The purpose is irrelevant to the effect on existing drivers and systems 
>>-- which is unknown.  Making the probe order independent of BIOS 
>>ordering may very well break drivers and systems that are dependent on 
>>BIOS ordering.  IOW what looks nice on your system could _likely_ suck 
>>for others.  That's what I meant by "x86 PCI code is very touchy."
>>    
>>
>
>That is why CONFIG_PCI_SORT_BY_BUS_SLOT_FUNC is off by default and
>even if it is on, you can still override it by passing "pci=nosort"
>or "pci=nobussort" to kernel.
>  
>

Sigh.  Repeating, the kernel is still bloated by your sorting function 
if CONFIG_PCI_SORT_BY_BUS_SLOT is not defined.  The function should go 
away if CONFIG_PCI_SORT_BY_BUS_SLOT is not defined.

    Jeff