Awesome! -- Jason Nieh http://www.cs.columbia.edu/~nieh On Nov 1, 2009, at 1:41 AM, Christoffer Dall <cd2436 at columbia.edu> wrote: > Hi all. > > After having spent almost two weeks chasing down a heisenbug and an > unwanted double prefetch abort I'm pretty happy to say that the guest > now successfully decompresses the kernel and actually starts executing > the main kernel initialization code. > > The bug, which caused the system to crash at random times was a simple > programming mistake, where I enabled interrupts for a few instructions > during exceptions handling. It has been fixed and guest execution with > or without hardware interrupts enabled (on the host machine) runs > stable and deterministically. The reason for the double prefetch abort > exception was also a programming error. The problem was that I forgot > to add the page offset for the second level page tables when creating > new second level page tables. When the prefetch was taken the second > time though, the L2 table was already created and in that case the > offset was added correctly and the mapping was created successfully. > Both bugs have been corrected in the main android-goldfish-2.6.27-virt > branch. > > The MMIO operations are now using the re-factored emulation code and > correctly decodes type, length, address and direction of load/store > operations and uses this to return to QEMU for IO emulation. On the > next vcpu run ioctl call from QEMU, the kernel code checks if the last > exit was due to an mmio-read and if so, places the code from QEMU into > the right register. > > I placed a screenshot of the guest printing "Uncompressing linux..." > on the wiki: http://android.chazy.dk. > > The crash which can be seen in the screenshot will be the main focus > of my work in the nearest future together with determining why some > characters are dropped in the mmio operations. There will also be some > more work in cleaning up the emulation code to make it all kernel > style and easier to maintain. > > Best, > Christoffer > _______________________________________________ > Android-virt mailing list > Android-virt at lists.cs.columbia.edu > https://lists.cs.columbia.edu/cucslists/listinfo/android-virt >
