On Sat, 2 Apr 2016 00:46:46 +0200 Lukas Wunner <lukas@xxxxxxxxx> wrote: > Hi Chris, > > On Fri, Apr 01, 2016 at 12:13:46AM +0100, Chris Bainbridge wrote: > > On Tue, Mar 29, 2016 at 07:41:30PM +0200, Lukas Wunner wrote: > > > Broadcom 4331 wireless cards built into Apple Macs unleash an IRQ storm > > > on boot until they are reset, causing spurious interrupts if the IRQ is > > > shared. Apparently the EFI bootloader enables the device and does not > > > disable it before passing control to the OS. The bootloader contains a > > > driver for the wireless card which allows it to phone home to Cupertino. > > > This is used for Internet Recovery (download and install OS X images) > > > and probably also for Back to My Mac (remote access, RFC 6281) and to > > > discover stolen hardware. > > > > > > The issue is most pronounced on 2011 and 2012 MacBook Pros where the IRQ > > > is shared with 3 other devices (Light Ridge Thunderbolt controller, SDXC > > > reader, HDA card on discrete GPU). As soon as an interrupt handler is > > > installed for one of these devices, the ensuing storm of spurious IRQs > > > causes the kernel to disable the IRQ and switch to polling. This lasts > > > until the b43 driver loads and resets the device. > > > > > > Loading the b43 driver first is not always an option, in particular with > > > the Light Ridge Thunderbolt controller: The PCI hotplug IRQ handler gets > > > installed early on because it is built in, unlike b43 which is usually > > > a module. > > > > > > Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=79301 > > > Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=895951 > > > Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1009819 > > > Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1149632 > > > > Should also fix https://bugzilla.kernel.org/show_bug.cgi?id=111781 ? > > Given that this is a serious bug that can corrupt filesystems it would > > be good to see the fix in stable too. > > I cannot reproduce this particular issue on my MBP9,1 even though it > is architecturally very similar to your MBP10,2. I tested it with > "iommu=force intel_iommu=on", blacklisted b43 and stressed the machine > a bit with kernel compiles. No issues. I think you will have to stress the wireless, not the kernel. Enable iommu and let the wireless receive packets that go through the hw filters. If you have a calm network and nobody sends data to you, the card won't write anything to DMA. (This all depends on how the firmware configured the filters). -- Michael
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