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Re: [Qemu-devel] [PATCH v2] xenfb: remove xen_init_display "temporary" h
From: |
Stefano Stabellini |
Subject: |
Re: [Qemu-devel] [PATCH v2] xenfb: remove xen_init_display "temporary" hack |
Date: |
Thu, 6 Jul 2017 16:37:14 -0700 (PDT) |
User-agent: |
Alpine 2.10 (DEB 1266 2009-07-14) |
On Thu, 29 Jun 2017, Paul Durrant wrote:
> > -----Original Message-----
> > From: Stefano Stabellini [mailto:address@hidden
> > Sent: 28 June 2017 19:37
> > To: address@hidden; address@hidden
> > Cc: address@hidden; address@hidden; Anthony Perard
> > <address@hidden>; address@hidden; Paul Durrant
> > <address@hidden>
> > Subject: [PATCH v2] xenfb: remove xen_init_display "temporary" hack
> >
> > Initialize xenfb properly, as all other backends, from its own
> > "initialise" function.
> >
> > Signed-off-by: Stefano Stabellini <address@hidden>
> >
> > ---
> > Changes in v2:
> > - remove xen_init_display from xen_backend.h
> > - handle cases where vkbd is missing
> >
> > diff --git a/hw/display/xenfb.c b/hw/display/xenfb.c
> > index e76c0d8..3b0168b 100644
> > --- a/hw/display/xenfb.c
> > +++ b/hw/display/xenfb.c
> > @@ -71,7 +71,6 @@ struct XenFB {
> > int fbpages;
> > int feature_update;
> > int bug_trigger;
> > - int have_console;
> > int do_resize;
> >
> > struct {
> > @@ -80,6 +79,7 @@ struct XenFB {
> > int up_count;
> > int up_fullscreen;
> > };
> > +static const GraphicHwOps xenfb_ops;
> >
> > /* -------------------------------------------------------------------- */
> >
> > @@ -855,6 +855,8 @@ static int fb_init(struct XenDevice *xendev)
> > static int fb_initialise(struct XenDevice *xendev)
> > {
> > struct XenFB *fb = container_of(xendev, struct XenFB, c.xendev);
> > + struct XenDevice *xin;
> > + struct XenInput *in;
>
> I think the scope of 'in' can be limited to the 'else' clause where it is
> used below.
>
> > struct xenfb_page *fb_page;
> > int videoram;
> > int rc;
> > @@ -877,16 +879,16 @@ static int fb_initialise(struct XenDevice *xendev)
> > if (rc != 0)
> > return rc;
> >
> > -#if 0 /* handled in xen_init_display() for now */
> > - if (!fb->have_console) {
> > - fb->c.ds = graphic_console_init(xenfb_update,
> > - xenfb_invalidate,
> > - NULL,
> > - NULL,
> > - fb);
> > - fb->have_console = 1;
> > + fb->c.con = graphic_console_init(NULL, 0, &xenfb_ops, fb);
> > +
> > + xin = xen_pv_find_xendev("vkbd", xen_domid, 0);
> > + if (xin == NULL) {
> > + xen_pv_printf(xendev, 1, "xenfb is up, but vkbd is not present\n");
> > + } else {
> > + in = container_of(xin, struct XenInput, c.xendev);
> > + in->c.con = fb->c.con;
>
> I notice that in->c.con is tested in input_initialise() and it will fail if
> NULL, so there is an inherent race between the frontends and also processing
> of xenstore watches. That seems a little fragile at best, but the dependency
> of input_initialise() on in->c.con is also somewhat bogus as the vkbd backend
> is created for xenfv machine types whereas xenfb is only there for xenpv
> machine types. I think this needs to be fixed before xenfb can be relied on
> to initialize correctly in all circumstances.
Yes, you are right that it is fragile. Also, there is no need for this
dependency: I'll remove it, and use qemu_console_lookup_by_index
instead.
Owen's patch will take care of making the qemu_console_lookup_by_index
call conditional on xenfb->raw_pointer_wanted != 1.
> > + xen_be_check_state(xin);
> > }
> > -#endif
> >
> > if (xenstore_read_fe_int(xendev, "feature-update", &fb-
> > >feature_update) == -1)
> > fb->feature_update = 0;
> > @@ -972,42 +974,3 @@ static const GraphicHwOps xenfb_ops = {
> > .gfx_update = xenfb_update,
> > .update_interval = xenfb_update_interval,
> > };
> > -
> > -/*
> > - * FIXME/TODO: Kill this.
> > - * Temporary needed while DisplayState reorganization is in flight.
> > - */
> > -void xen_init_display(int domid)
> > -{
> > - struct XenDevice *xfb, *xin;
> > - struct XenFB *fb;
> > - struct XenInput *in;
> > - int i = 0;
> > -
> > -wait_more:
> > - i++;
> > - main_loop_wait(true);
> > - xfb = xen_pv_find_xendev("vfb", domid, 0);
> > - xin = xen_pv_find_xendev("vkbd", domid, 0);
> > - if (!xfb || !xin) {
> > - if (i < 256) {
> > - usleep(10000);
> > - goto wait_more;
> > - }
> > - xen_pv_printf(NULL, 1, "displaystate setup failed\n");
> > - return;
> > - }
> > -
> > - /* vfb */
> > - fb = container_of(xfb, struct XenFB, c.xendev);
> > - fb->c.con = graphic_console_init(NULL, 0, &xenfb_ops, fb);
> > - fb->have_console = 1;
> > -
> > - /* vkbd */
> > - in = container_of(xin, struct XenInput, c.xendev);
> > - in->c.con = fb->c.con;
> > -
> > - /* retry ->init() */
> > - xen_be_check_state(xin);
> > - xen_be_check_state(xfb);
> > -}
> > diff --git a/hw/xenpv/xen_machine_pv.c b/hw/xenpv/xen_machine_pv.c
> > index 79aef4e..31d2f25 100644
> > --- a/hw/xenpv/xen_machine_pv.c
> > +++ b/hw/xenpv/xen_machine_pv.c
> > @@ -94,9 +94,6 @@ static void xen_init_pv(MachineState *machine)
> >
> > /* config cleanup hook */
> > atexit(xen_config_cleanup);
> > -
> > - /* setup framebuffer */
> > - xen_init_display(xen_domid);
> > }
> >
> > static void xenpv_machine_init(MachineClass *mc)
> > diff --git a/include/hw/xen/xen_backend.h
> > b/include/hw/xen/xen_backend.h
> > index 852c2ea..8a6fbcb 100644
> > --- a/include/hw/xen/xen_backend.h
> > +++ b/include/hw/xen/xen_backend.h
> > @@ -55,8 +55,6 @@ extern struct XenDevOps xen_netdev_ops; /*
> > xen_nic.c */
> > extern struct XenDevOps xen_usb_ops; /* xen-usb.c */
> > #endif
> >
> > -void xen_init_display(int domid);
> > -
> > /* configuration (aka xenbus setup) */
> > void xen_config_cleanup(void);
> > int xen_config_dev_blk(DriveInfo *disk);
>
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