Re: [Xen-devel] Xen optimization

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxx>]

On Sat, 13 Oct 2018, Milan Boberic wrote:
> > This is definitely wrong. Can you please also post the full host device
> > tree with your modifications that you are using for Xen and Dom0?  You
> > should have something like:
> >
> >         timer@ff110000 {
> >             compatible = "cdns,ttc";
> >             interrupt-parent = <0x2>;
> >             interrupts = <0x0 0x24 0x4 0x0 0x25 0x4 0x0 0x26 0x4>;
> >             reg = <0x0 0xff110000 0x0 0x1000>;
> >             timer-width = <0x20>;
> >             power-domains = <0x3b>;
> >             xen,passthrough;
> >         };
> > For each of the nodes of the devices you are assigning to the DomU.
> 
> I put
> &ttc0 {
>    xen,passthrough = <0x1>;
> };
> because when I was making bm app I was following this guide. Now I see
> it's wrong. When I copied directly:
> timer@ff110000 {
>             compatible = "cdns,ttc";
>             interrupt-parent = <0x2>;
>             interrupts = <0x0 0x24 0x4 0x0 0x25 0x4 0x0 0x26 0x4>;
>             reg = <0x0 0xff110000 0x0 0x1000>;
>             timer-width = <0x20>;
>             power-domains = <0x3b>;
>             xen,passthrough;
>         };
> in to the xen-overlay.dtsi file it resulted an error during
> device-tree build. I modified it a little bit so I can get successful
> build, there are all device-tree files included in attachment. I'm not
> sure how to set this passthrough properly, if you could take a look at
> those files in attachment I'd be more then grateful.
>
> > It's here: 
> > https://github.com/Xilinx/xen/blob/xilinx/stable-4.9/xen/arch/arm/vgic.c#L462
> Oh, about that. I sent you wrong branch, I was using Xen 4.10. Anyway
> now I moved to Xen 4.11 like you suggested and applied your patch and
> Dario's also.
> 
> Okay, now when I want to xl create my domU (bare-metal app) I get error:
> 
> Parsing config from timer.cfg
> (XEN) IRQ 68 is already used by domain 0
> libxl: error: libxl_create.c:1354:domcreate_launch_dm: Domain 1:failed
> give domain access to irq 68: Device or resource busy
> libxl: error: libxl_domain.c:1034:libxl__destroy_domid: Domain
> 1:Non-existant domain
> libxl: error: libxl_domain.c:993:domain_destroy_callback: Domain
> 1:Unable to destroy guest
> libxl: error: libxl_domain.c:920:domain_destroy_cb: Domain
> 1:Destruction of domain failed

That means that the "xen,passthrough" addition to the host device tree went 
wrong.


> I guess my modifications of:
> timer@ff110000 {
>             compatible = "cdns,ttc";
>             interrupt-parent = <0x2>;
>             interrupts = <0x0 0x24 0x4 0x0 0x25 0x4 0x0 0x26 0x4>;
>             reg = <0x0 0xff110000 0x0 0x1000>;
>             timer-width = <0x20>;
>             power-domains = <0x3b>;
>             xen,passthrough;
>         };
> are not correct.

Right


> I tried to change interrupts to:
>  interrupts = <0x0 0x44 0x4 0x0 0x45 0x4 0x0 0x46 0x4>;
> because if you check here on page 310 interrupts for TTC0 are 68:70.
> But that didn't work either I still get same error.

The interrupt numbers specified in the DTS are the real interrupt minus
32: 68-32 = 36 = 0x24. The DTS was correct.


> I also tried to change xen,passthrough; line with:
> xen,passthrough = <0x1>;
> but also without success, still the same error.
> 
> Are you sure about this line:
> reg = <0x0 0xff110000 0x0 0x1000>;   ?
> Or it should be like this?
>  reg = <0x0 0xff110000 0x1000>;

Yes, that could be a problem. The format depends on the #address-cells
and #size-cells parameters. You didn't send me system-conf.dtsi, so I
don't know for sure which one of the two is right. In any case, you
should not duplicate the timer@ff110000 node in device tree. You should
only add "xen,passthrough;" to the existing timer@ff110000 node, which
is probably in system-conf.dtsi. So, avoid adding a new timer node to
xen-overlay.dtsi, and instead modify system-conf.dtsi.


> I also included xl dmesg and dmesg in attachments (after xl create of bm app).
> 
> Thanks in advance!
> 
> Milan
> 

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