Pkg xen devel - Jan 2014 - Bug#734761: xen-system-amd64: "XEN kernel detects 3GB RAM instead of 4GB"

Package: xen-system-amd64
Version: 4.1.4-3+deb7u1
Severity: normal


The xen kernel detects 3GB of memory instead of the full 4GB. When using the
"normal" kernel 4GB is detected.

On boot the 4GB is detected:
root at ams-tc1-xen27:~# dmesg |grep Mem
[    0.000000] Memory: 3226132k/4980736k available (3426k kernel code, 788180k
absent, 966424k reserved, 3312k data, 576k init)

But only 3GB is used:
root at ams-tc1-xen27:~# cat /proc/meminfo
MemTotal:        3259444 kB
MemFree:         3006884 kB
Buffers:           12012 kB
Cached:           141592 kB
SwapCached:            0 kB
Active:            94636 kB
Inactive:         106156 kB
Active(anon):      47208 kB
Inactive(anon):      860 kB
Active(file):      47428 kB
Inactive(file):   105296 kB
Unevictable:          48 kB
Mlocked:              48 kB
SwapTotal:       3919864 kB
SwapFree:        3919864 kB
Dirty:                 0 kB
Writeback:             0 kB
AnonPages:         47256 kB
Mapped:             9548 kB
Shmem:               876 kB
Slab:              23628 kB
SReclaimable:      12628 kB
SUnreclaim:        11000 kB
KernelStack:         792 kB
PageTables:         2440 kB
NFS_Unstable:          0 kB
Bounce:                0 kB
WritebackTmp:          0 kB
CommitLimit:     5549584 kB
Committed_AS:     153956 kB
VmallocTotal:   34359738367 kB
VmallocUsed:       38532 kB
VmallocChunk:   34359697148 kB
HardwareCorrupted:     0 kB
AnonHugePages:         0 kB
HugePages_Total:       0
HugePages_Free:        0
HugePages_Rsvd:        0
HugePages_Surp:        0
Hugepagesize:       2048 kB
DirectMap4k:     4193024 kB
DirectMap2M:           0 kB



-- System Information:
Debian Release: 7.3
  APT prefers stable-updates
  APT policy: (500, 'stable-updates'), (500, 'stable')
Architecture: amd64 (x86_64)

Kernel: Linux 3.2.0-4-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash

Versions of packages xen-system-amd64 depends on:
ii  xen-hypervisor-4.1-amd64  4.1.4-3+deb7u1
ii  xen-utils-4.1             4.1.4-3+deb7u1

xen-system-amd64 recommends no packages.

xen-system-amd64 suggests no packages.

-- no debconf information

On Thu, 2014-01-09 at 17:37 +0100, Maarten de Wolff
wrote:
> The xen kernel detects 3GB of memory instead of the full 4GB. When
> using the "normal" kernel 4GB is detected.
> 
> On boot the 4GB is detected:
> root at ams-tc1-xen27:~# dmesg |grep Mem
> [    0.000000] Memory: 3226132k/4980736k available (3426k kernel code,
788180k absent, 966424k reserved, 3312k data, 576k init)
> 
> But only 3GB is used:
This only tells you what dom0 is seeing/using. What does "xl info" (or
"xm info") tell you about the whole system?

This might relate to the issue described in
http://blog.xen.org/index.php/2012/04/30/memory-where-it-has-not-gone/
http://wiki.xen.org/wiki/Do%EF%BB%BFm0_Memory_%E2%80%94_Where_It_Has_Not_Gone
	
Ian.

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