Messages in this thread |  | | | Date | Thu, 06 Jul 2000 13:50:03 -0600 | | From | "Jeff V. Merkey" <> | | Subject | Re: 2.2.15 driver OK on UP - no ints on SMP (SOLVED) |
| |
Linus,
When we were putting SMP on NetWare, we discovered that using the IOAPIC hardware for UP systems was almost 4% faster than the 8259-PIC for LAN drivers (since it has a dedicated ICC bus to pass interrupt messages to a local APIC). Something to consider.... :-)
Jeff
Linus Torvalds wrote: > > In article <Pine.LNX.3.96.1000706123221.6690B-100000@thing2.opinicus.com>, > William Montgomery <william@opinicus.com> wrote: > > > >So how can my driver my driver work fine in UP and not in SMP when > >using the pci_read_config* calls? > > On UP, we don't generally use the IO-APIC and it's more advanced irq > routing features. So on a regular UP compile, there will be a 1:1 > relationship between what the device _thinks_ the irq is, and what it > truly is.. > > >My workaround is to use > > struct pci_dev *dev; > >and when pci_find_device() inits dev, I use dev->irq instead of > > pci_read_config_byte(dev, PCI_INTERRUPT_LINE, &irq); > > > >Can anyone explain this? > > The above is not a work-around. It's the way you are supposed to work. > > In fact, drivers should generally _never_ look at the "generic" part of > the PCI config space, because that part has been parsed for them by the > kernel, which does a whole lot better job of it than most drivers can > ever do. This includes more than just figuring out what the _real_ > interrupt routing is. The generic PCI layer does a good job of figuring > out what resources the device has, of what type they are, and how large > they are. And it enables them correctly. Something that is usually a > lot more code than is good for you in a regular driver. > > For example, on multi-bus systems (especially 64-bit sparcs with > multiple PCI buses mapped in strange ways), you should not do the config > byte read to figure out where your memory aperture is: you should use > the data in "struct pci_dev *dev" instead, notably you should use the > functions especially created for them: things like > > start = pci_resource_start(dev,nr); > > to get at the resource start address. Because again, as with the > interrupt number, the device itself does not know what the global system > mapping is (it so happens that on PC's it's a 1:1 mapping, but that's > not always the case). > > Linus > > - > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.rutgers.edu > Please read the FAQ at http://www.tux.org/lkml/
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.tux.org/lkml/
|  |