On Tue, 2008-09-02 at 15:29 +0800, Liu Yu-B13201 wrote: > Hollis, > > I noticed fuction virtio_blk_update_config() (qemu/hw/virtio-blk.c) in > qemu > updated the virtio disk's capacity in little endian. > But virtblk_probe() (drivers/block/virtio_blk.c) in kernel read the > capacity from I/O space without convertion. Sigh, I don't remember why this works any more. There was discussion on this on kvm-ppc-devel in April (unfortunately it was right at the month line, so the threading is broken, but see e.g. http://marc.info/?l=kvm-ppc&m=120716463602156), and ultimately cpu_to_le64() was added to qemu. However, a couple weeks later, the swapping that the kernel was doing was removed (see http://thread.gmane.org/gmane.linux.kernel.virtualization/5776/focus=5801). However, the code is actually working today on 440 (and reporting a sane number of blocks). Also, this patch (http://article.gmane.org/gmane.linux.kernel.virtualization/6126/match=virtio%5fblk+fix+endianess+annotations) suggests that struct virtio_blk_config is no longer LE, so I'm thinking your problem must be in qemu. AFAICS the kernel is basically just doing memcpy in a few places. > Since E500 is big endian, this bring the misunderstanding between qemu > and guest. What are you using for PCI emulation in qemu? I don't think it should matter in this case, since the kernel is doing 1-byte reads in vp_get(), but endianness gets very convoluted wherever qemu is involved. :( -- Hollis Blanchard IBM Linux Technology Center -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
