Re: [dpdk-dev] [RFC] igb_uio: deprecate iomem and ioport mapping

[David Marchand <david.marchand@6wind.com>]

Hello Jianfeng,

On Thu, Sep 1, 2016 at 4:16 AM, Jianfeng Tan <jianfeng.tan@intel.com> wrote:
> Previously in igb_uio, iomem is mapped, and both ioport and io mem
> are recorded into uio framework, which is duplicated and makes the
> code too complex.
>
> For iomem, DPDK user space code never opens or reads files under
> /sys/pci/bus/devices/xxxx:xx:xx.x/uio/uioY/maps/. Instead,
> /sys/pci/bus/devices/xxxx:xx:xx.x/resourceY are used to map device
> memory.
>
> For ioport, non-x86 platforms cannot read from files under
> /sys/pci/bus/devices/xxxx:xx:xx.x/uio/uioY/portio/ directly, because
> non-x86 platforms need to map port region for access in user space,
> see non-x86 version pci_uio_ioport_map(). x86 platforms can use the
> the same way as uio_pci_generic.
>
> This patch deprecates iomem and ioport mapping in igb_uio kernel
> module, and adjusts the iomem implementation in both igb_uio and
> uio_pci_generic:
>   - for x86 platform, get ports info from /proc/ioports;
>   - for non-x86 platform, map and get ports info by pci_uio_ioport_map().
>
> Note: this will affect those applications who are using files under
> /sys/pci/bus/devices/xxxx:xx:xx.x/uio/uioY/maps/ and
> /sys/pci/bus/devices/xxxx:xx:xx.x/uio/uioY/portio/.
>
> Signed-off-by: Jianfeng Tan <jianfeng.tan@intel.com>
> ---
>  lib/librte_eal/linuxapp/eal/eal_pci.c     |   4 -
>  lib/librte_eal/linuxapp/eal/eal_pci_uio.c |  56 +-------------
>  lib/librte_eal/linuxapp/igb_uio/igb_uio.c | 119 ++----------------------------
>  3 files changed, 9 insertions(+), 170 deletions(-)

[snip]

> diff --git a/lib/librte_eal/linuxapp/eal/eal_pci_uio.c b/lib/librte_eal/linuxapp/eal/eal_pci_uio.c
> index 1786b75..28d09ed 100644
> --- a/lib/librte_eal/linuxapp/eal/eal_pci_uio.c
> +++ b/lib/librte_eal/linuxapp/eal/eal_pci_uio.c

[snip]

> -       /* FIXME only for primary process ? */
> -       if (dev->intr_handle.type == RTE_INTR_HANDLE_UNKNOWN) {
> -
> -               snprintf(filename, sizeof(filename), "/dev/uio%u", uio_num);
> -               dev->intr_handle.fd = open(filename, O_RDWR);
> -               if (dev->intr_handle.fd < 0) {
> -                       RTE_LOG(ERR, EAL, "Cannot open %s: %s\n",
> -                               filename, strerror(errno));
> -                       return -1;
> -               }
> -               dev->intr_handle.type = RTE_INTR_HANDLE_UIO;
> -       }

The only potential issue I can see removing this is that if a device
has no iomem resource, then its interrupt fd will never be
initialised.
I can see no problem at the moment, so let's go with this.
If such a problem arises later, we can separate this from the resource
mapping stuff (with a new api ?).

The rest looks good to me.

As Ferruh said, this should go through deprecation notices then go in 17.02.


-- 
David Marchand