From mboxrd@z Thu Jan  1 00:00:00 1970
From: Thomas Monjalon <thomas@monjalon.net>
Subject: Re: [PATCH v2 1/2] eal: add uevent api for hot plug
Date: Wed, 05 Jul 2017 09:32:11 +0200
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Cc: dev@dpdk.org, helin.zhang@intel.com, jingjing.wu@intel.com
To: "Guo, Jia" <jia.guo@intel.com>
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05/07/2017 05:02, Guo, Jia:
> hi, thomas
> 
> 
> On 7/5/2017 7:45 AM, Thomas Monjalon wrote:
> > Hi,
> >
> > This is an interesting step for hotplug in DPDK.
> >
> > 28/06/2017 13:07, Jeff Guo:
> >> +       netlink_fd = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_KOBJECT_UEVENT);
> > It is monitoring the whole system...
> >
> >> +int
> >> +rte_uevent_get(int fd, struct rte_uevent *uevent)
> >> +{
> >> +       int ret;
> >> +       char buf[RTE_UEVENT_MSG_LEN];
> >> +
> >> +       memset(uevent, 0, sizeof(struct rte_uevent));
> >> +       memset(buf, 0, RTE_UEVENT_MSG_LEN);
> >> +
> >> +       ret = recv(fd, buf, RTE_UEVENT_MSG_LEN - 1, MSG_DONTWAIT);
> > ... and it is read from this function called by one driver.
> > It cannot work without a global dispatch.
> the rte_uevent-connect is called in func of pci_uio_alloc_resource, so 
> each socket is created by  by each uio device. so i think that would not 
> affect each driver isolate to use it.

Ah OK, I missed it.

> > It must be a global mechanism, probably a service core.
> > The question is also to know whether it should be a mandatory
> > service in DPDK or an optional helper?
> a global mechanism would be good, but so far, include mlx driver, we all 
> handle the hot plug event in driver by app's registered callback. maybe 
> a better global would be try in the future. but now is would work for all
> pci uio device.

mlx drivers have a special connection to the kernel through the associated
mlx kernel drivers. That's why the PMD handle the events in a specific way.

You are adding event handling for UIO.
Now we need also VFIO.

I am wondering how it could be better integrated in the bus layer.

> and more, if in pci uio device to use hot plug , i think it might be 
> mandatory.