misc questions about the device&driver arch

Scott Long scottl at samsco.org
Tue May 30 07:29:35 PDT 2006

M. Warner Losh wrote:
> : Because the PCIE configure space is 4k long ,shall we change the
> : #define PCI_REGMAX	255
> : to facilitate the PCI express config R/W?
> Maybe.  Lemme investigate because PCIe changes this from a well known
> constant for all pci busses, to a variable one...
> Warner

When I added PCIe extended config support, I never took into
consderation the userland access point of view.  Changing this
definition to 4096 might Just Work, and it might Not Work.  Dunno.
In the 18 months since I implemented it, no other person has asked
about userland access.  Other than the silly case of people trying
to write device drivers in PERL, I'm not sure how much value it
gives compared to the stability and security risk it imposes.


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