KVM PPC execution doesn't use firmware today. Instead we create the device tree in qemu itself, stuff it into guest memory, and point a guest register at it on entry. This was just a shortcut/hack, because we didn't have enough time to enable both Linux and uboot. I agree that the best way to do things long-term is to run u-boot inside the guest environment. That will likely require improvements to qemu's device emulation, and also we'll probably need to work out a way for qemu to pass parameters (e.g. memory size) to u-boot. IMHO, the best approach there would be to have u-boot interpret a device tree from qemu, then modify it and pass it on to the kernel. Obviously that will require u-boot work. -Hollis On Sun, Jun 14, 2009 at 11:40 PM, Baojun Wang wrote: > It seems most boards will converted to the device tree infrastructure? > > but I think we will need a firmware first before loading the linux > kernel, I don't know if qemu-system-ppcemb could run kernel directly > without a firmware.. > > Best Regards, > Wang > > On Mon, Jun 15, 2009 at 3:46 AM, Hollis Blanchard > wrote: > > My 440 board is inaccessible for a couple weeks, so I can't test your > > patch. That said, the code looks fine. > > > > However, I wonder what your goal is? You want to be able to create a > > Bamboo board with e.g. a 750 processor? I don't think that would help > > the original poster, and I'm not sure how useful it is, but I don't > > object... > > > > Either way I guess it will become a non-issue once PowerPC boards are > > converted to the device tree infrastructure. > > > > -Hollis > > > > On Sun, Jun 14, 2009 at 1:33 PM, Blue Swirl wrote: > >> Sorry, I was very confused (I didn't look at ppc440.c). > >> > >> For some reason, CPU model can't be specified on the command line. The > >> patch allows this, does it look OK? > >> > >> Is there a kernel and initrd somewhere, so I could test this? > >> > >> Currently I get (no kernel or ROM, so nothing to execute): > >> Truncating memory to 128 MiB to fit SDRAM controller limits. > >> ppc405_serial_init: offset 0000000000000300 > >> QEMU 0.10.50 monitor - type 'help' for more information > >> (qemu) qemu: fatal: Trying to execute code outside RAM or ROM at > >> 0x00000000fffffffc > >> > >> NIP 00000000fffffffc LR 0000000000000000 CTR 0000000000000000 XER > 00000000 > >> MSR 0000000000000000 HID0 0000000000000300 HF 0000000000000000 idx 1 > >> Segmentation fault > >> > >> On 6/14/09, Hollis Blanchard wrote: > >>> Yes, I wrote the code you quoted. > >>> > >>> In case there is any confusion, let me restate: You can boot a Bamboo > >>> (PowerPC 440) guest under KVM on a PowerPC 440 host. KVM bypasses > >>> qemu's CPU emulation (TCG), but uses qemu's device emulation. > >>> Therefore, if someone were to implement 440 core emulation in qemu, > >>> you could boot a 440 kernel with qemu without KVM. > >>> > >>> Most devices found on 440 SoCs are the same as or very similar to the > >>> devices found on 405 SoCs. Qemu's 440 device emulation isn't perfect, > >>> but because Linux is highly modular, with a modified device tree you > >>> can boot it. See pc-bios/bamboo.dts. > >>> > >>> -Hollis > >>> > >>> On Sat, Jun 13, 2009 at 10:47 PM, Baojun Wang > wrote: > >>> > > >>> > in hw/ppc440.c: > >>> > > >>> > env = cpu_ppc_init("440EP"); > >>> > if (!env && kvm_enabled()) { > >>> > /* XXX Since qemu doesn't yet emulate 440, we just say it's a > 405. > >>> > * Since KVM doesn't use qemu's CPU emulation it seems to be > working > >>> > * OK. */ > >>> > env = cpu_ppc_init("405"); > >>> > } > >>> > if (!env) { > >>> > fprintf(stderr, "Unable to initialize CPU!\n"); > >>> > exit(1); > >>> > } > >>> > > >>> > also in hw/ppc.c: > >>> > > >>> > I can find ppc40x_irq_init/e500_irq_init(used mpc8544ds), but there > is > >>> > no ppcbooke_irq_init? It seems hw/ppc405_uc.c is emulation for DCRs, > >>> > PLB, DMA, GPIO, I2C.., but there is no hw/ppc44x_uc.c. > >>> > > >>> > the qemu source I used is 0.10.5. > >>> > > >>> > Also in ppc/translate_init.c, there lots of CONFIG_USER_ONLY, but I > >>> > many of them are DEBUG or CACHE related SPR emulation, and since > qemu > >>> > doesn't emulate cache, I think it's OK. > >>> > > >>> > Thanks, > >>> > Wang > >>> > > >>> > On Sun, Jun 14, 2009 at 1:47 AM, Hollis Blanchard< > hollis@penguinppc.org> wrote: > >>> > > On Fri, Jun 12, 2009 at 10:48 AM, Blue Swirl < > blauwirbel@gmail.com> wrote: > >>> > >> > >>> > >> On 6/11/09, Baojun Wang wrote: > >>> > >> > could qemu emulate some board like bamboo (without kvm) or > MPC8544ds > >>> > >> > now? Thanks > >>> > >> > >>> > >> Yes, if someone adds emulation for these devices: UIC, PLB, DMA, > POB, > >>> > >> EBC, IIC, ZMII. Maybe some are not needed in all cases. > >>> > > > >>> > > No, qemu still doesn't emulate Book E cores, such as the PowerPC > 440 in a > >>> > > Bamboo board. > >>> > > > >>> > > UIC is of course emulated, otherwise KVM guests on 440 wouldn't > get very > >>> > > far. :) Enough 440 SoC devices are emulated to support Linux boot > with a > >>> > > properly stripped device tree. > >>> > > > >>> > > -Hollis > >>> > > > >>> > >> > > >