Hi, I'm using RHEL4 kernel (2.6.9), and am trying to make PCI Express Native Hot-plug driver (pciehp) work on my system (My system has two hot-pluggable PCI Express slots). I am facing following problem, and would really appreciate if any one can provide any info regarding this problem. When I disable the ACPI support in my kernel configuration, the ("non-acpi") pciehp driver inserts successfully and I see the following two entries appearing in my /sys/bus/pci/slots: drwxr-xr-x 2 root root 0 Sep 2 14:28 10 drwxr-xr-x 2 root root 0 Sep 2 14:28 11 However, when I enable the ACPI support in the kernel, the controller initialization fails giving me following error (excerpts): ...... ...... pciehp: pfar:cannot locate acpi bridge of PCI 0xb. pciehp: pciehprm_find_available_resources = 0xffffffff pciehp: unable to locate PCI configuration resources for hot plug add. ...... ...... pciehp: pfar:cannot locate acpi bridge of PCI 0xe. pciehp: pciehprm_find_available_resources = 0xffffffff pciehp: unable to locate PCI configuration resources for hot plug add. ...... ...... I am attaching both the logs (The one with ACPI enabled and giving this error, the other - ACPI disabled and displaying the slot entries). I am not sure where the problem lies. But the fact that the entries are appearing correctly when I disable ACPI, combined with above error messages, I suspect that there is a problem with ACPI namespace (probably the resources cannot be found using ACPI). I have two questions: 1) How can I go about tackling this problem? The possibility of BIOS / Hardware being faulty cannot be ruled out. But then what exactly is missing and how can that be solved? 2) If the resources are actually missing, then how does the driver find the required resources when I disable the ACPI from kernel? Even if no body had faced this problem before, I would really appreciate if any one can provide ANY kind of pointers / information regarding this (As I am willing to explore and solve this, no matter what :-)) TIA Rajat Jain -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/