Description of problem: The RHEL5 qemu/kvm (0.10 based) does not properly emulate RTC Alarm (AIE) interrupts. Newer kernels (2.6.38+) use AIE interrupts exclusively for RTC functionality (including UIE mode). This manifests in issues like the following, when running recent guest kernels on a RHEL5 kvm host system. [root@hwclock ~]# hwclock select() to /dev/rtc to wait for clock tick timed out Proper AIE mode emulation was added to qemu/kvm in 0.11. While it is non-trivial, I think backporting the AIE support to the RHEL5 qemu/kvm package would be the best solution here. Version-Release number of selected component (if applicable): KVM version: 0.10.50 How reproducible: Always when using 2.6.38+ kernels. Steps to Reproduce: 1. Boot 2.6.38+ kernel with RHEL5 kvm 2. Run hwclock (or any other application that accesses the rtc with AIE or UIE mode irqs) Actual results: No interrupts when in UIE or AIE mode, causing applications to fail. Expected results: UIE and AIE mode interrupts should function, and applications would run normally. Additional info: This issue was originally reported here: https://bugzilla.kernel.org/show_bug.cgi?id=36252
can reproduce it with fedora guest, so add qe_ack + 1). #hwclock select() to /dev/rtc to wait for clock tick timed out 2). guest 2.6.38.6-26.rc1.fc15.x86_64 3). kvm: kvm-83-239.el5
We are considering a back-port of qemu upstream commit f292787d9addffd5f0a2df9516c158bfb5792b61 to address the RTC Alarm Interrupt issue. Additionally, we are considering a back-port of qemu upstream commit 98815437f731372d9456f6a2ad103f3b836a9646 The two combined patches should make rtc_update_second2() similar to RHEL6 code.
1.reproduce with kmod-kvm-83-239.el5 and 2.6.38.6-26.rc1.fc15.x86_64 steps to reproduce 1.1. install fedora15 guest 1.2.boot guest /usr/libexec/qemu-kvm -M rhel5.6.0 -m 4096 -smp 4,cores=2,threads=1,sockets=2 -cpu qemu64,vendor="AuthenticAMD",+sse2 -soundhw all -name win7 -usbdevice tablet -rtc-td-hack -uuid 123465d2-2032-848d-bda0-de7adb149048 -boot nc -drive file=/home/fedora/fedora15.qcow2,if=virtio,boot=on,bus=0,unit=0,format=qcow2,cache=none,boot=on,werror=stop -net nic,macaddr=54:52:00:27:12:23,vlan=0,model=virtio -soundhw ac97 -net tap,vlan=0,script=/etc/qemu-ifup -serial pty -parallel none -usb -balloon none -monitor stdio -spice host=0,ic=on,port=5911,disable-ticketing -qxl 1 1.3.# hwclock actual result: select() to /dev/rtc to wait for clock tick timed out 2.verify with kvm-83-246.el5 and 2.6.38.6-26.rc1.fc15.x86_64 2.1.repeat 1.1 2.2.repeat 1.2 2.3 repeat 1.3 actual result: # hwclock Mon 12 Dec 2011 06:02:06 AM EST -0.184707 seconds base on above testing result, this bug is fixed.
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. http://rhn.redhat.com/errata/RHSA-2012-0149.html