Re: FW: [PATCH 13/17] mlx4: Add blue flame support for kernel consumers

[Eli Cohen <eli@dev.mellanox.co.il>]

> 
> On Mon, Mar 7, 2011 at 2:17 AM, Yevgeny Petrilin
> <yevgenyp@mellanox.co.il> wrote:
> > +       if (map_bf_area(dev))
> > +               mlx4_dbg(dev, "Kernel support for blue flame is not available for kernels < 2.6.28\n");
> 
> This seems like a really bad error message.  Can map_bf_area() actually fail?

I agree that this message is inappropriate here; it is originiated
from the OFED patches which support older kernels too.
As for the question if a message is justified here at all, I think the
answer is yes becuase of this:

+static int map_bf_area(struct mlx4_dev *dev)
+{
+       struct mlx4_priv *priv = mlx4_priv(dev);
+       resource_size_t bf_start;
+       resource_size_t bf_len;
+       int err = 0;
+
+       bf_start = pci_resource_start(dev->pdev, 2) +
(dev->caps.num_uars << PAGE_SHIFT);
+       bf_len = pci_resource_len(dev->pdev, 2) - (dev->caps.num_uars
<< PAGE_SHIFT);
+       priv->bf_mapping = io_mapping_create_wc(bf_start, bf_len);
+       if (!priv->bf_mapping)
+               err = -ENOMEM;

Specifically, some archs may not support write combining.