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Re: [Xen-devel] Possible bug on ARM with irq passthrough



On 07/05/2017 01:27 PM, Julien Grall wrote:
On 04/07/17 21:20, Ivan Pavić2 wrote:
Hello,

Hi Ivan,

I'm testing IRQ latency on exynos5422. I'm using Xen 4.10-unstable. I used device passthrough for SPI irq 64. For guest domain I used FreeRTOS. When I use credit scheduler after destruction of domain, IRQ is released. I changed scheduler to credit2 and rtds at boot time and IRQ wasn't released after destruction. xl create dom-free-rtos.cfg fails with:

libxl: error: libxl_create.c:1278:domcreate_launch_dm: Domain 5:failed give domain access to irq 64: Device or resource busy

This is very strange because it doesn't happen with credit scheduler. This is output of xl dmesg:

(XEN) IRQ 64 is already used by domain 1

Everything works first time but when I destroy domain and try to create again it fails. It works normally with credit scheduler. In dom-free-rtos.cfg:
...
irqs = [64]
....

The Domain 1 still seems to be alive, you can confirm by via "xl list". You said it works with credit but not credit2. I think you hit the bug described in [1].
I checked xl-list. There is no domain with id 1, only dom0. Also I tried xenctx 1 which resulted in
    xc_domain_getinfo: No such process

Same problem is with rtds scheduler. As I said, no problem with credit scheduler.
Dario, do you have any status on this bug? I think we should consider it as a blocker for Xen 4.10.

Cheers,

[1] https://lists.xenproject.org/archives/html/xen-devel/2017-02/msg00138.html

Regards,

Ivan Pavic


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