Blue Swirl wrote: > On 10/1/07, Jocelyn Mayer <[EMAIL PROTECTED]> wrote: > > On Mon, 2007-10-01 at 17:55 +0300, Blue Swirl wrote: > > > On 10/1/07, Andreas Färber <[EMAIL PROTECTED]> wrote: > > > > > > > > Am 01.10.2007 um 09:12 schrieb Bob Deblier: > > > > > > > > > Ideally we should have an OpenBIOS compiled for QEMU/PPC. Is anyone > > > > > working on this? > > > > > > > > I had looked into this recently but it turned out that PearPC and > > > > others using OpenBIOS/ppc use an ELF format OpenBIOS binary that is > > > > incompatible with QEMU, expecting some raw image. I have no idea how > > > > to go about this; the (working) sparc version uses some "weird" > > > > assembler initializations. ;-) > > > > > > You can use: > > > objcopy -O binary in.elf out.bin > > > > > > Alternatively, Qemu could be enhanced to try loading ELF first and > > > binary if that fails. > > > > This is even not an option. With "normal" full system emulation, Qemu > > boots like real hardware does. I don't know any CPU able to load ELF > > images. As the goal is to emulate real hardware, what is to be given is > > a ROM image, able to boot a real machine.
FWIW, I don't regard the on-disk format of the BIOS as essential, as long as the emulated CPU sees the same bits as a real cpu does. Accepting ELF as a (possibly alternative) container for a BIOS image is a matter of convenience. > The effect is exactly the same from the emulated CPU perspective. With > ELF image we gain symbols in the out_asm dump. > > > You can try to ehance the -kernel option to do weird hacks if you like > > but the CPU state at the start of a normal boot process should be as > > near as possible as a real CPU after a hard reset. Any other behavior is > > a bug to fix asap. > > Imho Qemu can be a very great development tool (and I already used it > > for this purpose), not just a geek toy, then hacks that do not reflect > > what real hardware does have to be avoided any time it's possible. Then, > > adding an ELF loader in the CPU initialisation code seems to be a > > nonsense. The goal to achieve, imho, is to be able to run real ROM > > images extracted from real machine, not to "extend" the CPU features > > with stuffs that has no reality (and are even not useful as long as no > > machine would never accept to boot on this "firmware"). > > Qemu is not limited to just hardware emulation. Please consider for > example snapshot load/save support, built-in gdbstub and monitor. No > real hardware has any of these, or perhaps you could do similar things > with ICE or JTAG. > > Qemu is not also aimed for 100% accurate emulation of the hardware. > There are no caches or cycle counters and hardware devices run > unrealistically fast from CPU standpoint. Emulating performance > counters or the errata the most CPUs have would be extremely > difficult. I doubt Qemu CPU emulation can ever pass POST of real > BIOSes. I am working on making the Malta emulation boot a unaltered YAMON image. I don't see why a PC BIOS would be harder to accomodate. > Real BIOSes are also closed source, proprietary binary blobs. At least YAMON, CFE and PMON are not closed source. YAMON has a funny license which - I hope - will change. > Making open source BIOSes a viable alternative is in my opinion a much > more important goal. The one doesn't exclude the other. That said, I regard the ability to boot unaltered real-world firmare as an important test of the quality of a system emulation. Thiemo
