svn commit: r198431 - head/sys/dev/pci

Marcel Moolenaar xcllnt at
Mon Oct 26 16:33:05 UTC 2009

On Oct 26, 2009, at 5:37 AM, John Baldwin wrote:

>> Log:
>>  BIOSes, buggy or otherwise, are i386 or amd64 specific.
>>  Have the early USB takeover enabled for i386 and amd64
>>  by default.
>>  This also avoids a panic on PowerPC where the resource
>>  isn't released properly and we find a busy resource
>>  when the USB host controller wants to allocate it...

> Presumably such systems won't set the 'BIOS owned' bit in the their  
> legacy
> support registers in which case these routines are NOPs (they just  
> read the
> register, see the bit is clear, and exit).  The resource bug sounds  
> like a
> real one that should be fixed and would probably affect any x86  
> systems who
> have USB disabled in the BIOS, so that should be fixed rather than  
> papered
> over.  Please revert.


The change was made because 1) doing this as part of the PCI code is
unnecessary for non-PC HW, and 2) it's entirely untested on non-PC
HW and the gratuitous change can therefore only do harm -- he, guess
what, it did do harm.

Unless people fix the resource stuff this change cannot be reverted.

After the resource fix has gone in, I still object to this being
reverted on grounds of gratuitous code bloat. I say this with ARM,
MIPS and PowerPC/Book-E in mind.

> Note that the legacy support register stuff is part of the uhci/ohci/ 
> ehci
> specifications, and that the code to frob it has been part of the same
> drivers since their inception.  If it had been an actual problem  
> then it
> would have been disabled back when USB was enabled for other  
> architectures.

This is entirely besides the point...

Marcel Moolenaar
xcllnt at

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