During several tests with Qemu / Kqemu it seems that Qemu has problems with x86_64 host systems. My system is an AMD 64 X2 (Dual Core), running openSUSE 10.2, 2GB memory.
Various versions of Qemu/Kqemu available and under test: 0.8.2, 0.9.0, and CVS. Kqemu 1.3.0pre9, 1.3.0pre11 When building Qemu I use the following configure setup, using a gcc 3.4: ./configure --prefix=/usr/local/ \ --cc=/opt/gcc34/bin/gcc-3.4 --host-cc=/opt/gcc34/bin/gcc-3.4 \ --enable-alsa --enable-adlib \ --target-list="i386-softmmu x86_64-softmmu" Kqemu built with standard (system) gcc. I always use qemu-system-x86_64 to start Qemu. Here the problems: Installing a 32bit Linux system (Debian, Kernel 2.6.18): - works with pure Qemu (-no-kqemu) - fails with Kqemu support enabled. The failure is a loop before or during the kernel hands over control to INIT I used gdb to get some more information about the problems using the following command: gdb qemu-system-x86_64 using a .gdbinit that sets the args, etc. When the kernel goes into the loop I interrupt with ^C several times, most of the time it was in code_gen_buffer, here in the function "compute_c_subl". Because I'm _not_ sure this is the correct way to debug Qemu I cannot say if this is normal or not. At least the function always returns 1 (it seems that it is called over and over again with). The last relevant statement in this function is: cmp %eax,0x90(%r14) seta %al where the conetent of %eax is zero, the content of the memory is 0x00000000ffffeb3e. The return says: the memory content is bigger than 0x0 (which is true for 64bit, but also true for 32bit unsigned, "compute_c_subl" compares two unsigned 32bit integers). As said, take these findings with a grain of salt. My general thought about the problem: running 32bit code on a 64bit host with similar architecture as this is the case of x86 / x86_64 could easily result in problems with signedness, sign bit extension, different pointer/word/interger sizes... BTW: is there a Howto or other information how to debug Qemu when the loaded kernel loops or crashes? That would be great and would make it easier to step in here and provide some help (or is this a somewhat good kept secret :-) ? ). The next problems are fairly old, they are also reported in the Qemu user's wiki - but without an answer o solution. Installing a 64bit Linux system (openSuse 10.1, 10.2): - fails with Qemu (-no-kqemu), loops when Grub shall install the bootloader. - fails with Kqemu enabled, crashes at various addresses and prints register contents. Any hints what this could be? Solutions? Regards, Werner
