Re: [PATCH v5 0/4] uio: add MSI/MSI-X support to uio_pci_generic driver

From: Vlad Zolotarov
Date: Tue Oct 06 2015 - 16:48:33 EST




On 10/06/15 23:35, Vlad Zolotarov wrote:


On 10/06/15 21:27, Michael S. Tsirkin wrote:
On Tue, Oct 06, 2015 at 08:17:35PM +0300, Vlad Zolotarov wrote:
This series add support for MSI and MSI-X interrupts to uio_pci_generic driver.

Currently uio_pci_generic demands INT#x interrupts source be available. However
there are devices that simply don't have INT#x capability, for instance SR-IOV
VF devices that simply don't have INT#x capability. For such devices
uio_pci_generic will simply fail (more specifically its probe() will fail).

When IOMMU is either not available (e.g. Amazon EC2) or not acceptable due to
performance overhead and thus VFIO is not an option users that develop
user-space drivers are left without any option but to develop some proprietary
UIO drivers (e.g. igb_uio driver in Intel's DPDK) just to be able to use UIO
infrastructure.

This series provides a generic solution for this problem while preserving the
original behaviour for devices for which the original uio_pci_generic had worked
before (i.e. INT#x will be used by default).

New in v5:
- Expanded the commitlog on PATCH1.
Looks like you didn't attempt to address any of my review comments.
I don't intend to review this until you do.

So far there hasn't been any comments related to the code in these patches from your side but rather comments about the general flaws of the current uio_pci_generic in particular and UIO in general that have nothing to do with this series. Therefore obviously there was nothing to address.
If u have any comments related to _THIS_ series I'd be glad to address. So far I was under the strong impression that u develop an obviously theoretical discussion about "nice to have fixed" stuff in UIO, which was obvious to everybody on this thread had nothing to do with this patch series.

Could it be that I've got u wrong? If so, could u, pls., clarify what u'd like me to fix in these patches exactly and why?

I beg my pardon, there was one relevant comment of yours - to split the bars mapping into a separate patch. And this has been addressed. ;)


thanks,
vlad


New in v4:
- Use portable __u32 and __s32 types from asm/types.h for
defining uio_pci_generic_irq_set fields.
- Use proper _IO macros for defining read and write ioctl()
commands.
- Moved bars mapping setting into a separate patch.
- Update uio_pci_generic example in uio-howto.tmpl.

New in v3:
- Add __iomem qualifier to temp buffer receiving ioremap value.
New in v2:
- Added #include <linux/uaccess.h> to uio_pci_generic.c


Vlad Zolotarov (4):
uio: add ioctl support
uio_pci_generic: properly initialize PCI bars mappings towards UIO
uio_pci_generic: add MSI/MSI-X support
Documentation: update uio-howto

Documentation/DocBook/uio-howto.tmpl | 139 ++++++++++--
drivers/uio/uio.c | 15 ++
drivers/uio/uio_pci_generic.c | 409 +++++++++++++++++++++++++++++++++--
include/linux/uio_driver.h | 3 +
include/uapi/linux/uio_pci_generic.h | 51 +++++
5 files changed, 574 insertions(+), 43 deletions(-)
create mode 100644 include/uapi/linux/uio_pci_generic.h

--
2.1.0


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