Jan, On 10/26/2012 06:35 PM, Jan Kiszka wrote: > This has two problems: We know it breaks at least Win 95 that overwrites > its F-segment during boot. And it applies changes to the shadowed area > (below 1 MB) also to the ROM area - I don't think that is the original > behaviour on real hardware. So what is the problem? It can break Win95's running? I tried to install win95 guest but it failed to boot regardless my patchset was applied or not. I found the information that win 95 is not supported at http://www.linux-kvm.org/page/Guest_Support_Status Note: before my patchset, Win 95 still can happily something into ROM area because readonly memory is actually writable on KVM. And win95 can not run on isapc with --no-kvm since it is no way to enable shadow ROM. > > What we need is paravirtual shadow write control for the ISA PC. It's on > my todo list, maybe I will be able to look into this during the next week. > You idea is that modify the code of seabios and use a special way (PV) to notify Qemu to make the bios writable? Actually, I am confused why the guest (including bios) persistently uses shadow ROM even if it is not supported (on ISA PC), i think the right way is move itself to RAM under this case, no? > BTW, your patch series should allow to drop the KVM special case from > pc_system_firmware_init. That version, btw, treats high and low BIOS > areas separately - but only reloads the upper area. Hmm... > You mean that also allow Qemu to use pflash to load bios if kvm is enabled? We can not do that for pflash is a RD device which can not be directly written, kvm can not emulate the instruction which implicitly write the memory. (e.g: using this area as stack). Thanks! -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
