Grant Grundler <iod00d@hp.com> writes: > On Wed, Aug 04, 2004 at 07:07:04AM -0600, Eric W. Biederman wrote: > > Initially that patch > > was targeted for a kernel without device_shutdown(), so I was > > likely considering the old trick of running through all of the PCI > > devices and disabling their bus master bit. > > Blindly disabling all PCI bus master bits will also kill VGA/serial > console and any USB keyboard attached to the system. VGA/serial console devices rarely need to do be bus masters so they should be fine. > I'll comment more on the "DMA is a Red Herring" when I can read > more what it is about. Most of those cases don't matter as the driver should always be calling pci_set_master() on startup. Disabling all the bus master bits on ioxapics in pci space would likely cripple the system. As they are architectural hardware and rarely have pci drivers that can enable them. In the general case it appears to be overkill, incorrect and insufficient to disable bus mastering on all PCI devices. Which is why device_shutdown() calls device specific code. Eric - To unsubscribe from this list: send the line "unsubscribe linux-ia64" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.htmlReceived on Wed Aug 4 22:18:12 2004
This archive was generated by hypermail 2.1.8 : 2005-08-02 09:20:29 EST