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

[Christian Holpert <christian@xxxxxxxxxx>]

At 18:38 19.12.2012, you wrote:
> > >          e820: update [mem 0x00000000-0x0000ffff] usable ==> reserved
> > >          e820: remove [mem 0x000a0000-0x000fffff] usable
> > >         -e820: last_pfn = 0x80000 max_arch_pfn = 0x1000000
> > >         +e820: last_pfn = 0x20000 max_arch_pfn = 0x1000000
> >
> > I think the kernel has done the correct thing with the supplied e820 map.
> >
> > > On the libxl side with pci I also see:
> > >         +libxl: debug: 
> libxl_pci.c:85:libxl__create_pci_backend: Creating pci backend
> > >         +libxl: debug: libxl_x86.c:82:e820_sanitize: Memory: 
> 2097152kB End of RAM: 0x20000 (PFN) Delta: 1572864kB, PCI start: 
> 524288kB (0x20000 PFN), Balloon 0kB
> > >         +
> > >         +libxl: debug: libxl_x86.c:201:e820_sanitize: : [0 -> 20000] RAM
> >
> > This is the 512 MiB limit here, so I think the bug is in libxl.
>
> Correct.
> >
> > Why has it placed the PCI window at 512 MiB anyway?  3 GiB would be more
> > conventional.
>
> It "copies" what the E820 is and tries it best to sanitize it.
>
> But it looks to have missed the "RAM" chunks in from the 0->3GB.
>
> However, it should have made the 'Balloon' be much much bigger value.
> Something is off there. What type of machine is this? An Intel 
> DQSW..something?

Intel Core i5-3570 (Ivy Bridge Generation)
ASRock Q77M vPro
16GB RAM

/proc/cpuinfo
processor       : 0
vendor_id       : GenuineIntel
cpu family      : 6
model           : 58
model name      : Intel(R) Core(TM) i5-3570 CPU @ 3.40GHz
stepping        : 9
microcode       : 0x10
cpu MHz         : 3392.416
cache size      : 6144 KB
physical id     : 0
siblings        : 1
core id         : 0
cpu cores       : 1
apicid          : 0
initial apicid  : 0
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 13
wp              : yes
flags           : fpu de tsc msr pae cx8 apic cmov pat clflush acpi 
mmx fxsr sse sse2 ss ht nx constant_tsc nonstop_tsc pni pclmulqdq 
monitor est ssse3 sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes 
xsave avx f16c rdrand hypervisor ida arat epb xsaveopt pln pts dtherm 
fsgsbase erms
bogomips        : 6784.83
clflush size    : 64
cache_alignment : 64
address sizes   : 36 bits physical, 48 bits virtual
power management:

repeated as expected for quad-core.

Have tried to move to xen-4.2.1 today, but no change:
xen ~ # xl list
Name                                        ID   Mem VCPUs      State   Time(s)
Domain-0                                     0  9082     4     r-----      53.8
colin                                        1  2048     3     -b----      73.9
nodi                                         2   512     2     -b----     110.2
[...]

BTW: When I shutdown this domain now, I keep some leftovers:
xen xen # xl list
Name                                        ID   Mem VCPUs      State   Time(s)
Domain-0                                     0  7535     4     r-----      78.2
colin                                        1  2048     3     -b----      91.6
(null)                                       2     6     2     --ps-d     144.6
print                                        3  2048     3     -b----       5.0
web                                          4  1024     2     -b----      12.7
nodi                                         5   512     2     ---s--      52.9
xen xen #

xen xen # xl list
Name                                        ID   Mem VCPUs      State   Time(s)
Domain-0                                     0  7529     4     r-----      85.2
colin                                        1  2048     3     -b----     102.3
(null)                                       2     6     2     --ps-d     144.6
print                                        3  2048     3     -b----       5.1
web                                          4  1024     2     -b----      13.1
(null)                                       5     6     2     --ps-d      52.9
nodi                                         6   512     2     r-----      13.6
xen xen #

xen xen # xl info 2
host                   : xen
release                : 3.4.11-gentoo
version                : #7 SMP Mon Dec 3 20:37:13 CET 2012
machine                : i686
nr_cpus                : 4
max_cpu_id             : 3
nr_nodes               : 1
cores_per_socket       : 4
threads_per_core       : 1
cpu_mhz                : 3392
hw_caps                : 
bfebfbff:28100000:00000000:00007f40:77bae3ff:00000000:00000001:00000281
virt_caps              : hvm hvm_directio
total_memory           : 15778
free_memory            : 2446
sharing_freed_memory   : 0
sharing_used_memory    : 0
free_cpus              : 0
xen_major              : 4
xen_minor              : 2
xen_extra              : .1
xen_caps               : xen-3.0-x86_32p hvm-3.0-x86_32 hvm-3.0-x86_32p
xen_scheduler          : credit
xen_pagesize           : 4096
platform_params        : virt_start=0xf5800000
xen_changeset          : unavailable
xen_commandline        : vtd=1 iommu=1 vga=gfx-1024x768x16 msi=1
cc_compiler            : gcc (Gentoo 4.7.2 p1.3, pie-0.5.5) 4.7.2
cc_compile_by          :
cc_compile_domain      : APO43287A.LOCAL
cc_compile_date        : Wed Dec 19 20:22:58 CET 2012
xend_config_format     : 4
xen xen #

Never seen this with 4.2.0.

nodi is the only domain with pci-passthrough.

Christian


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