On 19.01.2011 [15:06:20 +1100], Benjamin Herrenschmidt wrote:

On Tue, 2011-01-18 at 14:47 -0800, Nishanth Aravamudan wrote:

quoted

On 18.01.2011 [12:31:52 +1100], Anton Blanchard wrote:

quoted

Hi,

I was testing 2.6.37-git17 on a POWER7 with virtual IO and hit this:

Trying to unpack rootfs image as initramfs...
Freeing initrd memory: 7446k freed
vio 30000000: Warning: IOMMU dma not supported: mask
0xffffffffffffffff, table unavailable
vio 4000: Warning: IOMMU dma not supported: mask 0xffffffffffffffff,
table unavailable
vio 4001: Warning: IOMMU dma not supported: mask 0xffffffffffffffff,
table unavailable
vio 4002: Warning: IOMMU dma not supported: mask 0xffffffffffffffff,
table unavailable
vio 4004: Warning: IOMMU dma not supported: mask 0xffffffffffffffff,
table unavailable
audit: initializing netlink socket (disabled)

Haven't had a chance to look closer yet.

Well, this causes messages for vdevices that don't do DMA at all (such
as vterm etc...) and don't have the necessary properties. However, it
didn't -break- anything for me in my tests so far, just spurrious
messages. Not sure what's up with Anton's setup. Anton, can you hack the
printk to display the OF path to the device so we see what devices are
complaining ? It could be a different issue that prevents booting.

Is this what you were looking for?

vio 30000000: Warning: IOMMU dma not supported: mask 0xffffffffffffffff, table unavailable
vio 30000000: Path: /vdevice/vty@30000000
vio 4000: Warning: IOMMU dma not supported: mask 0xffffffffffffffff, table unavailable
vio 4000: Path: /vdevice/IBM,sp@4000
vio 4001: Warning: IOMMU dma not supported: mask 0xffffffffffffffff, table unavailable
vio 4001: Path: /vdevice/rtc@4001
vio 4002: Warning: IOMMU dma not supported: mask 0xffffffffffffffff, table unavailable
vio 4002: Path: /vdevice/nvram@4002
vio 4004: Warning: IOMMU dma not supported: mask 0xffffffffffffffff, table unavailable
vio 4004: Path: /vdevice/gscsi@4004

FWIW, I looked at Anton's logs, and I don't think the boot failed, per
se. I think it may have timed out (but not positive on that). I was able
to boot 2.6.27-git17 on the exact same box, albeit it locks up at a
later point (the sd abort I e-mailed about in a follow-up).

Cheers,
Ben.

quoted

After debugging a bit, this would appear to be due to the second hunk of
b3c73856ae47d43d0d181f9de1c1c6c0820c4515.

diff --git a/arch/powerpc/kernel/vio.c b/arch/powerpc/kernel/vio.c
index b265405..1b695fd 100644
--- a/arch/powerpc/kernel/vio.c
+++ b/arch/powerpc/kernel/vio.c

@@ -1257,6 +1257,10 @@ struct vio_dev *vio_register_device_node(struct device_node *of_node)
        viodev->dev.parent = &vio_bus_device.dev;
        viodev->dev.bus = &vio_bus_type;
        viodev->dev.release = vio_dev_release;
+        /* needed to ensure proper operation of coherent allocations
+         * later, in case driver doesn't set it explicitly */
+        dma_set_mask(&viodev->dev, DMA_BIT_MASK(64));
+        dma_set_coherent_mask(&viodev->dev, DMA_BIT_MASK(64));

        /* register with generic device framework */
        if (device_register(&viodev->dev)) {

Milton, Sonny, any thoughts?

Thanks,
Nish

-- 
Nishanth Aravamudan [off-list ref]
IBM Linux Technology Center