Re: [PATCH V2] drivers/uio/uio.c: DMA mapping, interrupt extensions, etc.

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On 04/15/2010 11:55 PM, Tom Lyon wrote:
This is the second of 2 related, but independent, patches. This is for
uio.c, the previous is for uio_pci_generic.c.

The 2 patches were previously one large patch. Changes for this version:
- uio_pci_generic.c just gets extensions so that a single fd can be used
   by non-privileged processes for interrupt control and mmaps
- All of the DMA and IOMMU related stuff move to uio.c; no longer a need
   to pass ioctls to individual uio drivers. It turns out that the code
   is not PCI specific anyways.
- A new ioctl to pin DMA buffers to certain IO virtual addresses for KVM.
- New eventfd based interrupt notifications, including support for PCI
   specific MSI and MSI-X interrupts.
- PCI specific code to reset PCI functions before and after use


@@ -122,4 +126,23 @@
  #define UIO_PORT_GPIO	2
  #define UIO_PORT_OTHER	3

+#endif	/* __KERNEL__ */
+
+// Kernel&  User level defines for ioctls
+
+struct uio_dma_map {
+	unsigned long	vaddr;
+	unsigned long long dmaaddr;

Use __u64 for both, otherwise you need to rewrite the structures in the kernel in case 32-bit userspace calls a 64-bit kernel.

+	int	size;

What units? Size is probably too small. Suggest unsigned type to avoid an extra check in the kernel.

+	int	rdwr;

What values can this hold?

+};
+
+#define	UIO_DMA_MAP_ANYWHERE	_IOWR(';', 100, struct uio_dma_map)

What does this do?  Ignore vaddr?

+#define	UIO_DMA_MAP_IOVA	_IOWR(';', 101, struct uio_dma_map)
+#define	UIO_DMA_UNMAP		_IOW(';', 102, struct uio_dma_map)
+#define	UIO_DMA_MASK		_IOW(';', 103, unsigned long long)
+#define	UIO_EVENTFD_IRQ		_IOW(';', 104, int)
+#define	UIO_EVENTFD_MSI		_IOW(';', 105, int)
+#define	UIO_EVENTFDS_MSIX	_IOW(';', 106, int)

These three need some documentation.


--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.

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