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;
>
> ???
> > 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
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