On Wed, Apr 11, 2012 at 01:45:45PM +0200, Arend van Spriel wrote: > On 03/19/2012 10:51 PM, Matthew Garrett wrote: > > > >I'm dealing with a platform with some buggy system firmware that enables > >DMA on the wireless card and leaves it running even after OS handover, > > From what you showed me we are dealing with a MacBook Air using > UEFI. As our meeting was brief I may have misunderstood, but am I > correct to say the wireless card is active with UEFI mode to allow > wireless network selection for netboot or something like that? Yes. > I also assume the proper fix should be to have the system firmware > shutdown the wireless device properly before OS handover. My guess > is that the device is still doing DMA transfers to some physical > address space which is OK in UEFI context but the OS has assigned it > for something else. That seems to be exactly the problem. > >triggering memory corruption. I'm working around that by disabling bus > >mastering on the device in the bootloader, but that results in the > >system hanging during brcmsmac init. pci_set_master() is being called in > >the bcma code, so it's nothing that straghtforward. Any idea what might > >be going wrong here? > > > > You showed me a boot menu. So after selecting Fedora the system is > moving to the grub bootloader first? Yup. > Are you disabling bus master or the entire wireless device? Could > you try disabling the device in the bootloader, ie. > pci_disable_device() or something equivalent. I'm just disabling the bus mastering. Do you expect there to be a behavioural difference in the core if I disable BAR decoding as well? -- Matthew Garrett | mjg59@xxxxxxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
