On (Thu) Sep 03 2009 [19:56:05], Amit Shah wrote:
> Hi Juan,
>
> On (Thu) Sep 03 2009 [16:06:54], Juan Quintela wrote:
> > > diff --git a/hw/virtio-console.c b/hw/virtio-console.c
> > > index 663c8b9..da590d2 100644
> > > --- a/hw/virtio-console.c
> > > +++ b/hw/virtio-console.c
> > >
> > > #include "hw.h"
> > > +#include "monitor.h"
> > > +#include "pci.h"
> > > +#include "sys-queue.h"
> > > #include "qemu-char.h"
> > > #include "virtio.h"
> > > #include "virtio-console.h"
> > >
> > > -
> > > typedef struct VirtIOConsole
> > > {
> > > VirtIODevice vdev;
> > > - VirtQueue *ivq, *dvq;
> > > - CharDriverState *chr;
> > > + PCIDevice *dev;
> >
> > Why do you need dev here? VirtIODevice already have hidded somewhere
> > a PCIDevice (hidded is a good defenition).
> > virtio-blk and virtio-net are able to work with that pci device.
>
> Let me check that; I need pci device while initialising a new port (and
> it's slightly different when done at init and when done at hot-add
> time).
>
> > > +/* Readiness of the guest to accept data on a port */
> > > +static int vcon_can_read(void *opaque)
> > > +{
> > > + VirtIOConsolePort *port = (VirtIOConsolePort *) opaque;
> >
> > Cast is not needed here.
>
> This is original code that I've not modified (just moved around).
>
> But you're right; I could do that in this patch itself.
>
> > > +static void virtio_console_set_port_active(uint32_t idx)
> > > +{
> > > + int i = 0;
> > > +
> > > + while (idx / 32) {
> > > + i++;
> > > + idx -= 32;
> > > + }
> >
> > It is just me, or you are doing a division + modulus in a very strange way?
> >
> > i = idx / 32;
> > idx = idx % 32;
> >
> > ???
Er, sorry I left this out.
That won't work for MAX_PORTS > 32.
But I guess I can just do
i = idx / MAX_VIRTIO_CONSOLE_PORTS;
idx = idx % MAX_VIRTIO_CONSOLE_PORTS;
> > > static void virtio_console_save(QEMUFile *f, void *opaque)
> > > {
> > > VirtIOConsole *s = opaque;
> > > + unsigned int i;
> > >
> > > + /* The virtio device */
> > > virtio_save(&s->vdev, f);
> > > + /* The PCI device */
> > > + pci_device_save(s->dev, f);
> >
> > If you don't use pci here, virtio_save() should save your pci stuff
> > here. See the ->load_config() stuff.
> >
> > Yeap, it can confuse anybody.
>
> Actually no. Since virtio rides on top of pci, I'd expect virtio_save to
> save pci state too :-)
>
> I'll check this too.
>
> > For the new table based vmstate, fields need to live in an struct, in
> > this case VirtIOConsole.
> >
> > Can you move virtcon_config and virtcon_ports to VirtIOConsole.
>
> In that case VirtIOConsole has to become a static (instead of being
> allocated via the call to virtio_common_init. Doable.
>
> > > + /* The config space */
> > > + qemu_put_be16s(f, &virtcon_config.cols);
> > > + qemu_put_be16s(f, &virtcon_config.rows);
> >
> > > + qemu_put_be32s(f, &virtcon_config.max_nr_ports);
> > > + qemu_put_be32s(f, &virtcon_config.nr_active_ports);
> > > + for (i = 0; i < (le32_to_cpu(virtcon_config.max_nr_ports) + 31) / 32; i++) {
> > > + qemu_put_be32s(f, &virtcon_config.ports_map[i]);
> > > + }
> >
> > Don't even try to save a couple of bytes, please.
>
> Sorry, don't understand this.
>
> >
> > for (i = 0; i < (MAX_VIRTIO_CONSOLES + 31) / 32; i++) {
> > qemu_put_be32s(f, &virtcon_config.ports_map[i]);
> > }
> >
> > Same for load, please. Makes the translation to table based way easier.
>
> OK, maybe I now get it. You're asking me not to le32_to_cpu() here,
> correct?
>
> I do it this way because we could be migrated from a host that supports
> 64 max ports to a host that supports 128 max ports and then back to the
> one that supports 64 max ports. :-)
>
> > > + /* Items in struct VirtIOConsole */
> > > + qemu_put_be32s(f, &virtio_console->guest_features);
> >
> > here you mean s->guest_features, right?
>
> Right!
>
> > > + /* Items in struct VirtIOConsolePort */
> > > + for (i = 0; i < le32_to_cpu(virtcon_config.max_nr_ports); i++) {
> > > + qemu_put_byte(f, virtcon_ports[i].guest_connected);
> > > + }
> >
> > If you want to optimize saving of this field, it is possible that it is
> > a better idea to create another bitmap for it. What do you think?
>
> Yes, I wanted to do that as well. The same functions that compute the
> modulo/division earlier can give us this thing as well. But it'll only
> be used for loadvm/savevm. I expect the bool to continue to reside in
> this struct for normal operation.
>
> > I can't see VMState adding support for bools any time soon, but arrays
> > of bool is a possibility.
>
> Consider the RFE filed :-)
>
> > > @@ -128,19 +610,29 @@ VirtIODevice *virtio_console_init(DeviceState *dev)
> > > VirtIOConsole *s;
> > > s = (VirtIOConsole *)virtio_common_init("virtio-console",
> > > VIRTIO_ID_CONSOLE,
> > > - 0, sizeof(VirtIOConsole));
> > > + sizeof(struct virtio_console_config),
> > > + sizeof(VirtIOConsole));
> >
> > Here, you mean:
> >
> > VirtIODevice *d = virtio_common_init(....);
> > VirtIOConsole *s = DO_UPCAST(VirtIOConsole, vdev, d);
> >
> > :)
>
> Again original code, not my contributions :-)
>
> > Creation of VirtIODevice *d is not necesary, I found it easier to
> > understand but it is up to you.
>
> For virtio-serial, I statically allocated VirtIOSerial and had a vdev
> pointer inside it which virtio_common_init gave me. I can do the same
> here.
>
> > > if (s == NULL)
> > > return NULL;
> > >
> >
> > Once you are there, virtio_common_init() can't return NULL, fix it please.
>
> Original code. But I will take it.
>
> > > -#define MAX_VIRTIO_CONSOLES 1
> > > +#define MAX_VIRTIO_CONSOLE_PORTS 64
> >
> > Require that this number is a multiple of 32, and you can simplify all
> > the (foo + 31/32) staff.
>
> Sure, but it's better to be careful in a couple of places just because
> we can be. Does (foo+31)/32 make it very difficult to read?
>
> Amit
> --
> http://log.amitshah.net/
>
>
Amit
--
To unsubscribe from this list: send the line "unsubscribe kvm" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
