[Xen-users] Re: [Xen-devel] Xen - Guest memory allocation

[dinesh chandrasekaran <dinesh_chan8@xxxxxxxxxxx>]

Hi,

             if I use the following inside the populate_physmap() inside xen/common/memory.c,

unsigned long maddr_pci = 0xdf000000;       //since I know the machine address of the mememory behind my pci device <xm dmesg>

static void populate_physmap(struct memop_args *a)
{
        /******              

             for(i=a->nr_done; i<a->nr_extents; i++)
             {
                          /*************     
                 &nb sp;    if(d->is_privilaged)                       

		page = alloc_domheap_pages(d, a->extent_order, a->memflags | MEMF_node(node));
	  else 
	   {
		page = maddr_to_page(maddr_pci);
		maddr_pci = ((maddr + PAGE_SIZE-1) &PAGE_MASK);

`    ;                         }
                   /***************
                }
        printk("a->nr_done: %lx", a->nr_done);
   }
           
The printk says "a->nr_done: 2000" when 'xm dmesg' is used (which is correct since I allocated 32MB for DomU = 8192 pages = 0x2000)

but exits with the following error:

& n bsp;            'dmesg' says : Using config file "/home/guest/Guest.conf".
                       Error: (1, 'Internal error', 'xc_dom_boot_domU_map: failed to mmap domU pages 0x200+0x2e3 [xenctl, rc=-1]\n'
       
             'xm dmesg' says: <G><1>mm.c:671:d0 Non-privileged (1) attempt to map I/O space 000df1ff

Thanks,
Dinesh C



            

---

From: dinesh_chan8@xxxxxxxxxxx
To: xen-devel@xxxxxxxxxxxxxxxxxxx; xen-users@xxxxxxxxxxxxxxxxxxx
Date: Mon, 23 Jun 2008 05:50:44 +0530
Subject: FW: [Xen-users] Re: [Xen-devel] Xen - Guest memory allocation

Yeah milos,
                  But the PCI  device should be allowed access by all DomUs.
Hiding the device from Dom0 is not what I really want to achieve.
I have to stick to xen source code (and not dom0 or domU) to make this possible.

As ou said in the previous mail, Im working on the populate
_physmap() to force xen allocate memory for all domUs from the memory available
behind the PCI device.

I could not understand how hiding the PCI device from Dom0 related to my goal.

Thanks alot,
Dinesh C



> Date: Fri, 20 Jun 2008 18:03:20 +0100
> From: gm281@xxxxxxxxx
> To: dinesh_chan8@xxxxxxxxxxx
> Subject: Re: [Xen-users] Re: [Xen-devel] Xen - Guest memory allocation
> CC: xen-devel@xxxxxxxxxxxxxxxxxxx; xen-users@xxxxxxxxxxxxxxxxxxx
>
> >> Why do you want to restrict DomU to use frames fro m certain range
> >> only? What's the logic behind that?
> >
> > Im trying to allocate memory for domUs from memory behind a PCI device. The
> > machine_addr_start is obtained by probing the device (as I know the vendor
> > and device info) during xen boot-up.
>
> That's what I was suspecting. I think you should give PCI passthrough
> a go first.
> PCI passthrough allows a PCI device to be hidden away from Dom0 and
> exported to a DomU. You achieve the first by passing
> pciback.hide=(XX:XX.X) option to Dom0 kernel and adding pci = [
> 'XX:XX.X′ ] to DomU config file. You'll also need
> CONFIG_XEN_PCIDEV_FRONTEND=y and CONFIG_XEN_PCIDEV_BACKEND=y in your
> DomU and Dom0 kernel configs.
>
> Hope this helps
> Gr(z)egor(z)

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