Hi Philippe, On 03/03/2011 08:32 AM, Philippe Gerum wrote: > On Thu, 2011-03-03 at 08:21 +0100, Richard Cochran wrote: >> On Wed, Mar 02, 2011 at 07:18:46PM +0100, Jan Kiszka wrote: >>> On 2011-03-02 16:26, Gilles Chanteperdrix wrote: >>>> Richard Cochran wrote: >>>>> The wiki pages >>>>> >>>>> http://www.xenomai.org/index.php/FAQs >>>>> http://www.xenomai.org/index.php/Configuring_x86_kernels >>>>> >>>>> say not to enable MSI on x86, with a link to a very old (2008) >>>>> discussion. >> >> ... >> >>> The current situation looks like this: >>> - MSI[-X] usage for plain Linux drivers is fine, we are using it on >>> machines where you can hardly avoid MSI today >>> - MSI[-X] usage for RTDM (ie. RT) drivers is basically fine as long as >>> you avoid enabling/disabling from RT context (also used for quite >>> a while here, no known issues under this restriction) >> >> Okay, so I understand from this: >> >> 1. The wiki warning is out of date. >> >> 2. My own PCIe MSI driver/card *should* work. >> (It is not a current known limitation of adeos/xenomai.) > > The situation is not that clear. Enabling CONFIG_PCI_MSI on some 83xx > board did cause a lock up at boot for me, so this may point the finger > at the pipeline core for ppc, and not to Xenomai which was barely active > at that stage.
Now I remember vaguely that we have seen a similar issue on the mpc8308 in autumn last year. Here is what you wrote that time: On 09/29/2010 04:12 PM, Philippe Gerum wrote: > Ok, I have a good news: the issue is spotted; and a bad one: this is no > trivial stuff to fix. In short, CONFIG_PCI_MSI causes the PIC code to > read PCI config memory on the fly during operations (which is intensely > insane but that is how it goes). Of course, it does that via the regular > PCI helpers, which are stuffed with normal locking constructs we may > _not_ call from any real-time/non-regular context. > > To sum up, we need to call those helpers to ack/mask interrupts within > the I-pipe, but we are not allowed to do this because this is inherently > unsafe. > > Work-around: disable CONFIG_PCI_MSI in your configuration. > The real fix would require much more thought, to make the PCI helpers > Adeos-aware without inducing high latency. Wolfgang. _______________________________________________ Xenomai-help mailing list Xenomai-help@gna.org https://mail.gna.org/listinfo/xenomai-help
