Re: [Xen-devel] [Xen-users] DomU sees only 512MB RAM with PCI-passthrough

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Wed, May 29, 2013 at 05:23:42PM +0200, Christian Holpert wrote:
> ---- Original-Nachricht ----
>   Von: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
>   Datum: Mittwoch, 29. Mai 2013 17:02:32
> >So with a 2048 guest it boots for me. Here is the diff between
> >your kernel and mine:
> >
> >Can you try the v3.10 or v3.9 and see how it works for you?
> Tried out v3.10-rc3 and can confirm that your patch works.

Great! So something is off with v3.8 kernel. The hint seems
to be:

Populating 100000-160000 pfn range: 393216 pages added          Populating 
100000-160000 pfn range: 393216 pages added
..
Xen: [mem 0x0000000100000000-0x000000015fffffff] usable         Xen: [mem 
0x0000000100000000-0x000000015fffffff] usable
bootconsole [xenboot0] enabled                                <
NX (Execute Disable) protection: active                         NX (Execute 
Disable) protection: active
DMI not present or invalid.                                     DMI not present 
or invalid.
e820: last_pfn = 0x160000 max_arch_pfn = 0x1000000              e820: last_pfn 
= 0x160000 max_arch_pfn = 0x1000000
init_memory_mapping: [mem 0x00000000-0x2d3fdfff]              | Scanning 1 
areas for low memory corruption
(XEN) mm.c:864:d6 Non-privileged (6) attempt to map I/O space | 
init_memory_mapping: [mem 0x00000000-0x000fffff]
(XEN) mm.c:5317:d6 ptwr_emulate: could not get_page_from_l1e( | 
init_memory_mapping: [mem 0x1fe00000-0x1fffffff]
BUG: unable to handle kernel NULL pointer dereference at   (n | 
init_memory_mapping: [mem 0x1c000000-0x1fdfffff]
IP: [<c157fe96>] xen_set_pte_init+0x3b/0x43                   | 
init_memory_mapping: [mem 0x00100000-0x1bffffff]
*pdpt = 0000000000000000 *pde = c2c2c2c2c2c2c2c2              | RAMDISK: [mem 
0x01b51000-0x107b0fff]

That v3.8 is trying to allocate pages up to 2d3fdfff. Which we don't in v3.10.

But we do seem to use said area for HighMem (0x2d3fe000-0x5fffffff) which
works in v3.10.

Oops: 0003 [#1] SMP                                           | 4908MB HIGHMEM 
available.
Modules linked in:                                            | 723MB LOWMEM 
available.
Pid: 0, comm: swapper Not tainted 3.8.13-gentoo #1            |   mapped low 
ram: 0 - 20000000
EIP: e019:[<c157fe96>] EFLAGS: 00010046 CPU: 0                |   low ram: 0 - 
2d3fe000
EIP is at xen_set_pte_init+0x3b/0x43                          | Zone ranges:
EAX: c2380000 EBX: 00000000 ECX: 20000403 EDX: 20000403       |   DMA      [mem 
0x00001000-0x00ffffff]
ESI: 00020001 EDI: 00000000 EBP: 20000403 ESP: c1545e18       |   Normal   [mem 
0x01000000-0x2d3fdfff]
 DS: e021 ES: e021 FS: 00d8 GS: 00e0 SS: e021                 |   HighMem  [mem 
0x2d3fe000-0x5fffffff]
CR0: 80050033 CR2: 00000000 CR3: 015ec000 CR4: 00002660       | Movable zone 
start for each node
DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000       | Early memory 
node ranges
DR6: ffff0ff0 DR7: 00000400                                   |   node   0: 
[mem 0x00001000-0x0009ffff]
Process swapper (pid: 0, ti=c1544000 task=c1550120 task.ti=c1 |   node   0: 
[mem 0x00100000-0x1fffffff]
Stack:                                                        |   node   0: 
[mem 0x00000000-0x5fffffff]
 00000000 20000403 00000000 00020000 e0000000 c158f111 000000 | Using APIC 
driver default
 c15ec018 00000003 c15ec018 00000003 20000000 00000000 0002d3 | smpboot: 
Allowing 4 CPUs, 0 hotplug CPUs
 00000100 c2380000 00000001 00000000 fffe0000 0016d000 000000 | Local APIC 
disabled by BIOS -- you can enable it with "lapic"
Call Trace:                                                   | APIC: disable 
apic facility

Would need to dig in this deeper, but that looks to be
an issue with the kernel, not with the toolstack.

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