Problems with serial interrupts with IPMI 2.0 SoL

From: Jeremy Fitzhardinge
Date: Thu Dec 10 2009 - 16:46:05 EST


Hi,

I'm using a system with an embedded IPMI 2.0 BMC which provides SoL (Supermicro X8SIL-F). This works fine under Linux (fully interrupt driven), but fails for Xen as it appears to not be sending interrupts; it works OK if I set the driver to polling mode.

I'm assuming the Xen is tickling some bug in the emulated 16550. The Linux driver has a couple of pieces of code to explicitly work around bugs in the Intel AMT SoL implementation, but I don't think they're coming into play here (because there are no Intel SoL PCI devices on this system to trigger the NO_TXEN_TEST flag).

I'm wondering if you have any pointers or suggestions about more subtle problems?

Thanks,
J
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