rtc not in kernel ?


Active Member
Dec 10, 2009
[fixed] rtc not in kernel ?

EDIT: rtc is ok in kernel 2.6.35
# dmesg | grep -i rtc
rtc_cmos 00:03: RTC can wake from S4
rtc_cmos 00:03: rtc core: registered rtc_cmos as rtc0
rtc0: alarms up to one month, y3k, 114 bytes nvram, hpet irqs
rtc_cmos 00:03: setting system clock to 2010-11-10 09:23:21 UTC (1289381001)

but nothing in 1.6.32.
# dmesg | grep -i rtc

# uname -a
Linux xxxxxx 2.6.32-4-pve #1 SMP Thu Oct 21 09:35:29 CEST 2010 x86_64 GNU/Linux

I've upgraded all my servers to 2.6.35 as there is another bug in 2.6.32: the max memory of a Win2008 vm is 4Go, even if set to more in config.

having issues with RTC in my VMs, i found that the RTC device is not available !

I used the technique described below to find out:

Easy way to find out:

/sbin/modprobe rtc

If you get "module rtc not found", then your distro (or you) answered either Y or N to the CONFIG_RTC question when configuring. To find out which, skip down a bit.

If you get "module already loaded" or no output at all, then you have RTC support in your kernel already (CONFIG_RTC was set to M, and the module is now loaded). Continue with vmware. You may have to modprobe rtc before running vmware in the future (you can add aliases to /etc/modules.conf, or add rtc to /etc/modules if your distro supports that, to load it automatically).

To find out whether you answered Y or N to CONFIG_RTC, check whether you have a /proc/sys/dev/rtc directory. If you do, then CONFIG_RTC is definitely Y, so continue with the vmware install.

If you don't have that directory, then you'll need to recompile at least part of the kernel. If you have your present kernel's .config file, and the source for that exact version, you can just change CONFIG_RTC to M and do "make modules", then "cp drivers/char/rtc.ko /lib/modules/$(uname -r)/kernel/drivers/char/" if you run kernel 2.6, or "cp drivers/char/rtc.o /lib/modules/$(uname -r)/kernel/drivers/char/" if you have kernel 2.4.

So there is no /proc/sys/dev/rtc folder, and /sbin/modprobe rtc displays "module rtc not found".

Could you explain why ?
And how can i get rtc back ?

# pveversion -v
pve-manager: 1.6-5 (pve-manager/1.6/5261)
running kernel: 2.6.35-1-pve
proxmox-ve-2.6.35: 1.6-7
pve-kernel-2.6.32-3-pve: 2.6.32-18
pve-kernel-2.6.32-4-pve: 2.6.32-25
pve-kernel-2.6.35-1-pve: 2.6.35-7
qemu-server: 1.1-22
pve-firmware: 1.0-9
libpve-storage-perl: 1.0-14
vncterm: 0.9-2
vzctl: 3.0.24-1pve4
vzdump: 1.2-8
vzprocps: 2.0.11-1dso2
vzquota: 3.0.11-1dso1
pve-qemu-kvm: 0.12.5-2
ksm-control-daemon: 1.0-4

#cat /proc/cpuinfo
Intel(R) Xeon(R) CPU W3520 @ 2.67GHz
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov
pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx rdtscp lm c
onstant_tsc arch_perfmon pebs bts rep_good xtopology nonstop_tsc aperfmperf pni
dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm dca sse4_1 sse4_2 popcnt
lahf_lm ida dts tpr_shadow vnmi flexpriority ept vpid

# uname -a
Linux xxxxxx 2.6.35-1-pve #1 SMP Tue Oct 26 11:05:44 CEST 2010 x86_64 GNU/Linux

Thanks !
Last edited:


Proxmox Staff Member
Staff member
Aug 29, 2006
Re: [fixed] rtc not in kernel ?

I've upgraded all my servers to 2.6.35 as there is another bug in 2.6.32: the max memory of a Win2008 vm is 4Go, even if set to more in config.


Not here. Do you power off and start after you set the new memory? and do you use a 64-bit windows?


Active Member
Dec 10, 2009
and 2008 is only x64.

Got the same bug in 2.6.24, no rtc no memory over 4G.

Check the Max physical memory not the total memory which includes paging file.


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