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

[dinesh chandrasekaran <dinesh_chan8@xxxxxxxxxxx>]

Thanks MIlos,This was really helpful.
                             
> You can then allow
> DomU to use specific ranges of IO memory using
> XEN_DOMCTL_iomem_permission. Have a look how tools do it, when
> assigning a PCI device to a DomU:
> tools/python/xen/xend/server/pciif.py

But let the Dom0 take care of I/O pages for all DomUs (hope this is the default).
I'm just trying for the making Memory pages and NOT I/O pages for all DomUs available from the my_pci address range
using populate_physmap().

> You do need 'real' memory to be assigned to DomU.
Yeah. That is the reason why I used maddr_to_page() macro;

I assume that xen uses populate_physmap() to allocate 'real' memory  for all DomUs.
Is my assumption wrong?

Thanks,
Dinesh C

> Date: Mon, 30 Jun 2008 13:52:26 +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
>
> > Yes, about the I/O pages,
> > my machine uses 36-bit physical addresses,
> > since PCI address are all 32-bit, Im facing difficulties in converting these
> > addresses into pages using maddr_to_page();
>
> The bit widths are not the (main) problem!
> I don't think that patching populate_physmap is the right approach.
> You do need 'real' memory to be assigned to DomU. You can then allow
> DomU to use specific ranges of IO memory using
> XEN_DOMCTL_iomem_permission. Have a look how tools do it, when
> assigning a PCI device to a DomU:
> tools/python/xen/xend/server/pciif.py
>
>
> Cheers
> Gr(z)egor(z)
> >
> > So, I have to use a 64-bit PCI device.
> >
> > Thanks Milos,
> > Dinesh C
> >
> >
> >> Date: Sat, 28 Jun 2008 16:50:48 +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;
> >> derek.murray@xxxxxxxxxxxx
> >>
> >> > 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);
> >>
> >> This is going to assign DomU IO pages _only_.
> >>
> >> > maddr_pci = ((maddr + PAGE_SIZE-1) &PAGE_MASK);
> >>
> >> What is maddr here? Did you mean maddr_pci? Also, (page_aligned_x +
> >> PAGE_SIZE - 1) & PAGE_MASK = page_aligned_x, in other words you are
> >> stuck on the same page.
> >>
> >> >
> >> > ` &nbsp ; }
> >> > /***************
> >> > }
> >> > 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
> >>
> >> Dom0 tried map DomU memory in order to load the kernel + other boot
> >> info. This fails because you've only allocated IO pages to DomU.
> >>
> >> Cheers
> >> Gr(z)egor(z)
> >
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