[Xen-devel] Re: [Xen-changelog] Create /dev/xen/evtchn if it doesn't exist.

[Anthony Liguori <aliguori@xxxxxxxxxx>]

Another way to solve this problem is to just use "/dev/evtchn" as that 
is what will be created by udev.
In fact, what does everyone think about just deprecating /dev/xen/evtchn 
and just using /dev/evtchn everywhere?  I'll submit a patch if it's 
acceptable (including removing the places where we create /dev/xen/evtchn).
Regards,

Anthony Liguori

Xen patchbot -unstable wrote:

> # HG changeset patch
> # User shand@xxxxxxxxxxxxxxxxxxxxxxxxxxx
> # Node ID b7c7cb88f0ba9c0473d926c3cf531f9e086c3d09
> # Parent  7d0fb56b4a916cccc497d200e6a8329537ce740d
> Create /dev/xen/evtchn if it doesn't exist. 
>
> Signed-off-by: Steven Hand <steven@xxxxxxxxxxxxx>
>
> diff -r 7d0fb56b4a91 -r b7c7cb88f0ba tools/xenstore/xenstored_domain.c
> --- a/tools/xenstore/xenstored_domain.c Wed Sep  7 19:01:31 2005
> +++ b/tools/xenstore/xenstored_domain.c Wed Sep  7 20:30:00 2005
> @@ -433,33 +433,57 @@
> {
> }
>
> +#define EVTCHN_DEV_NAME  "/dev/xen/evtchn"
> +#define EVTCHN_DEV_MAJOR 10
> +#define EVTCHN_DEV_MINOR 201
> +
> /* Returns the event channel handle. */
> int domain_init(void)
> {
> -       /* The size of the ringbuffer: half a page minus head structure. */
> -       ringbuf_datasize = getpagesize() / 2 - sizeof(struct ringbuf_head);
> -
> -       xc_handle = talloc(talloc_autofree_context(), int);
> -       if (!xc_handle)
> -               barf_perror("Failed to allocate domain handle");
> -       *xc_handle = xc_interface_open();
> -       if (*xc_handle < 0)
> -               barf_perror("Failed to open connection to hypervisor");
> -       talloc_set_destructor(xc_handle, close_xc_handle);
> -
> +    /* The size of the ringbuffer: half a page minus head structure. */
> +    ringbuf_datasize = getpagesize() / 2 - sizeof(struct ringbuf_head);
> +    
> +    xc_handle = talloc(talloc_autofree_context(), int);
> +    if (!xc_handle)
> +        barf_perror("Failed to allocate domain handle");
> +
> +    *xc_handle = xc_interface_open();
> +    if (*xc_handle < 0)
> +        barf_perror("Failed to open connection to hypervisor (privcmd)");
> +
> +    talloc_set_destructor(xc_handle, close_xc_handle);
> +    
> #ifdef TESTING
> -       eventchn_fd = fake_open_eventchn();
> +    eventchn_fd = fake_open_eventchn();
> #else
> -       eventchn_fd = open("/dev/xen/evtchn", O_RDWR);
> +    {
> +        struct stat st;
> +        
> +        /* Make sure any existing device file links to correct device. */
> +        if ( (lstat(EVTCHN_DEV_NAME, &st) != 0) || !S_ISCHR(st.st_mode) ||
> +             (st.st_rdev != makedev(EVTCHN_DEV_MAJOR, EVTCHN_DEV_MINOR)) )
> +            (void)unlink(EVTCHN_DEV_NAME);
> +        
> +      reopen:
> +        eventchn_fd = open(EVTCHN_DEV_NAME, O_NONBLOCK|O_RDWR);
> +        if (eventchn_fd == -1) {
> +            if ((errno == ENOENT) && (
> +                    (mkdir("/dev/xen", 0755) == 0) || (errno == EEXIST)) 
> +                && (mknod(EVTCHN_DEV_NAME, S_IFCHR|0600,
> +                          makedev(EVTCHN_DEV_MAJOR,EVTCHN_DEV_MINOR)) == 0))
> +                goto reopen;
> +            return -errno;
> +        }
> +    }
> #endif
> -       if (eventchn_fd < 0)
> -               barf_perror("Failed to open connection to hypervisor");
> -
> -       if (xc_evtchn_bind_virq(*xc_handle, VIRQ_DOM_EXC, &virq_port))
> -               barf_perror("Failed to bind to domain exception virq");
> -
> -       if (ioctl(eventchn_fd, EVENTCHN_BIND, virq_port) != 0)
> -               barf_perror("Failed to bind to domain exception virq port");
> -
> -       return eventchn_fd;
> -}
> +    if (eventchn_fd < 0)
> +        barf_perror("Failed to open connection to hypervisor (evtchn)");
> +    
> +    if (xc_evtchn_bind_virq(*xc_handle, VIRQ_DOM_EXC, &virq_port))
> +        barf_perror("Failed to bind to domain exception virq");
> +    
> +    if (ioctl(eventchn_fd, EVENTCHN_BIND, virq_port) != 0)
> +        barf_perror("Failed to bind to domain exception virq port");
> +    
> +    return eventchn_fd;
> +}
>
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>  
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