On Mon, 2007-10-22 at 09:36 +0200, J. Mayer wrote: > Hi all, > > I've been investigating more about PreP kernel boot using Qemu and I > achieved to boot 2.4.35, 2.6.12 and 2.6.22 kernels using Qemu CVS and > unmodified OHW. > The issues I found in the kernel are: > - the OpenFirmware video console driver is broken in recent 2.4 kernels > and have been removed from recent 2.6 kernel > - I then decided to use the vga16fb console driver but needed to do some > patches in order to make it compile properly > - the CMOS RTC driver is not available for PPC architecture in 2.6 > kernels and need some patches in order to be usable > - I discovered that the mkprep utility is bugged in 2.4.35 and 2.6.12 > kernels. The bugs are visible only when cross-compiling from a > little-endian and/or 64 bits host. > - I got issues (ie process freezing) when using the 2.6.22 kernel with > HZ > 100. It seems to run properly when the system timer is set to 100 > Hz but this needs more tests for confirmation. > - I got the 2.6.22 kernel crashing (ie kernel Oops in workqueue code) > when it has no RTC available. There is no problem when the RTC is > present. This is likely to be a kernel bug: when no RTC is available, it > cannot calibrate its timers properly and the kernel timer seems to run > very fast. Forcing (with hacks...) the timer to run at nearly real-time > seems to prevent the bug to happen. > > I then generated some kernels that allow me to boot and use those 3 > kernels. > Here are 3 tarballs with: > - a patch to be applied to the vanilla kernel sources to fix the > mentionned bugs > - the .config file I used to build the kernel > - the zImage.prep image > <http://perso.magic.fr/l_indien/qemu-ppc/linux-tests/linux-2.4.35-prep.tar.bz2> > <http://perso.magic.fr/l_indien/qemu-ppc/linux-tests/linux-2.6.12-prep.tar.bz2> > <http://perso.magic.fr/l_indien/qemu-ppc/linux-tests/linux-2.6.22-prep.tar.bz2> > > I then run Qemu with the following command line template: > ./ppc-softmmu/qemu-system-ppc -serial stdio -net nic,model=ne2k_isa -net > tap -net nic,model=ne2k_pci -net tap -net nic,model=rtl8139 -net tap > -cpu 604 -M prep -L pc-bios/ -hda <my_first_disk> -cdrom <my_cdrom> > -kernel > <src_base>/linux-<kversion>.patched/arch/ppc/boot/images/zImage.prep > > Hope this helps.
Two points I forgot: - there is no way to make Qemu stop when the PreP kernel displays "Power down" because the prep_halt routine just does an infinite loop. - the board reset would not work with the current code. I will fix this soon. -- Jocelyn Mayer <[EMAIL PROTECTED]>
