On 10/1/07, Thiemo Seufer <[EMAIL PROTECTED]> wrote: > 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.
Emulating microcode, or firmware blobs loaded to misc devices. Think writing a BIOS for Transmeta, Alpha or a SoC. > > 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. Maybe. The CPU probes for cacheline size, checks for errata #42 vs #45, reads debug registers, attempts to identify the bus speed by comparing I/O access times, tries to verify the system using a TPM and fails all cases. What can you do?