Auf 10.03.2011 19:43, Jordan Justen schrieb: > On Thu, Mar 10, 2011 at 01:10, Avi Kivity <a...@redhat.com> wrote: > >> On 03/10/2011 06:51 AM, Jordan Justen wrote: >> >>> http://wiki.qemu.org/Features/System_Flash >>> >>> >> - make the programming interface the same as an existing device >> > How strongly do you feel about this? > > For one thing, real devices are not as flexible as QEMU for flash > sizes. QEMU allows for any 64kb multiple bios size. Real world > devices generally only support powers of 2 sizes. > > Firmware hub devices are somewhat simplistic to emulate, but I think > they use 16MB of address space, while only providing <= 1MB of flash > storage. >
Up to 4 MB on real hardware, and if you use Parallel flash devices, there is no limit at all (except cost). The software interface is identical for read/write/erase/probe. > SPI devices are available in many sizes, so it might be possible to > choose a 16MB device to emulate. But, it would be a lot more complex > to emulate as it would it involve emulating an SPI contoller + the > device. > I have written a SPI flash chip emulator (it emulates 3 different real-world SPI flash chips) and am willing to contribute it to Qemu if there is interest. The code is pretty small, and adding a SPI host controller emulator should be a few lines of code extra. Not a big problem. > I thought this might be a case where deviation from real hardware > emulation could better serve the VM's needs. > If we have to write the code anyway, and if it can work just fine with current KVM/Qemu, is there a reason not to use the same interface as real hardware? Regards, Carl-Daniel -- http://www.hailfinger.org/
