Hello! I am working on the Xen PCI front in the Jeremey's git tree: git://git.kernel.org/pub/scm/linux/kernel/git/jeremy/xen.git and trying to make the drivers/pci/xen-pcifront.c to be modularized. The reason for this is to slim down the kernel - there is no need for the PV-OPS kernel to have the xen-pcifront.c compiled in since most deployments aren't using it. The Xen PCI-front is a driver for the PV guest domains (on machines where you don't have VT-d) to have a channel with the privileged domain to operate on PCI devices. Basically a shim that intercepts pci_conf_[read|write] commands and forwards them to the control domain that can do the native pci_conf_[read|write] commands. It also can do MSI/MSI-X. The issue I am having is that during the driver initialization, it walks the PCI devices it has found. Keep in mind that the normal x86 PCI code has not found anything as the 0xcf8/0xcfc are not visible to the guest. Here is the issue I am hitting: 450 /* Claim resources before going "live" with our devices */ 451 pci_walk_bus(b, pcifront_claim_resource, pdev); If the xen-pcifront is compiled as module, the pci_walk_bus is not accessible as it does not have an EXPORT_SYMBOL. One way to resolve this is to make pci_walk_bus exportable but I don't know what the policy for this is? Is this the preferred method? Or should try another method, where I seperate the driver in two pieces: 1). One that stays in the kernel and will just find the PCI BARs and register them. 2) The other that actually does the shimming? But then I am back to the kernel having a compiled piece of code that is not used in most deployments. I would appreciate any ideas of how to do this correctly? Attached is simple patch (inline and attached) for the EXPORT_SYMB in case that is the right way of doing it. [PATCH] [PCI]: Export pci_walk_bus function. In preperation of modularizing Xen-pcifront (which is not in mainline - hopefully soon), the pci_walk_bus needs to be exported so that the xen-pcifront module can walk call the pci subsystem to walk the PCI devices and claim them. Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> --- drivers/pci/bus.c | 1 + 1 files changed, 1 insertions(+), 0 deletions(-) diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c index cef28a7..1805f3d 100644 --- a/drivers/pci/bus.c +++ b/drivers/pci/bus.c @@ -253,3 +253,4 @@ EXPORT_SYMBOL(pci_bus_alloc_resource); EXPORT_SYMBOL_GPL(pci_bus_add_device); EXPORT_SYMBOL(pci_bus_add_devices); EXPORT_SYMBOL(pci_enable_bridges); +EXPORT_SYMBOL(pci_walk_bus); -- 1.6.2.5
>From 54619378508ebb134ad3e669b485283bd9dc041b Mon Sep 17 00:00:00 2001 From: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> Date: Mon, 21 Dec 2009 11:24:21 -0500 Subject: [PATCH] [PCI]: Export pci_walk_bus function. In preperation of modularizing Xen-pcifront (which is not in mainline - hopefully soon), the pci_walk_bus needs to be exported so that the xen-pcifront module can walk call the pci subsystem to walk the PCI devices and claim them. Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> --- drivers/pci/bus.c | 1 + 1 files changed, 1 insertions(+), 0 deletions(-) diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c index cef28a7..1805f3d 100644 --- a/drivers/pci/bus.c +++ b/drivers/pci/bus.c @@ -253,3 +253,4 @@ EXPORT_SYMBOL(pci_bus_alloc_resource); EXPORT_SYMBOL_GPL(pci_bus_add_device); EXPORT_SYMBOL(pci_bus_add_devices); EXPORT_SYMBOL(pci_enable_bridges); +EXPORT_SYMBOL(pci_walk_bus); -- 1.6.2.5
