Am 20.02.2013 22:46, schrieb David Woodhouse:
> From: David Woodhouse <david.woodho...@intel.com>
>
> This implements reset functionality for the i440FX, resetting all the
> PAM registers to their power-on defaults of no RAM access and thus
> forwarding all access to the 0xc0000-0xfffff range to PCI address space
> (i.e. to the actual ROM) instead of RAM.
>
> Fixing this is sufficient to work around a KVM bug which causes it to
> run 16-bit code at 0xffff0 instead of 0xfffffff0 on CPU reset. If reset
> was working correctly on the i440FX, that KVM bug wouldn't have
> *mattered* because the two addresses would have identical contents.
>
> There's been much discussion about the distinction between hard reset
> and soft reset, and the fact that many of our reset triggers (such as
> the keyboard controller and triple-fault handler) are actually doing a
> full system-wide hard reset when in fact they should be triggering
> something much more limited in scope.
>
> This patch exacerbates that existing problem only slightly, by causing
> the offending triggers to reset yet another piece of hardware that they
> shouldn't have been resetting. But the problem is largely theoretical
> anyway; mostly limited to 80286 protected mode software which needs to
> initiate a CPU reset to get back into real mode, but which *doesn't*
> want a full system reset. Such software is almost certainly already
> broken under Qemu anyway, because of all the *other* aspects of a full
> hard reset that are already happening.
>
> So this patch can be applied separately from any longer-term fixes to
> make the 'soft' reset actually do the right thing.
>
> Signed-off-by: David Woodhouse <david.woodho...@intel.com>
> ---
> hw/piix_pci.c | 19 +++++++++++++++++++
> 1 file changed, 19 insertions(+)
>
> diff --git a/hw/piix_pci.c b/hw/piix_pci.c
> index 2eeb739..9e6eca0 100644
> --- a/hw/piix_pci.c
> +++ b/hw/piix_pci.c
> @@ -175,6 +175,24 @@ static int i440fx_load_old(QEMUFile* f, void *opaque,
> int version_id)
> return 0;
> }
>
> +static void i440fx_reset(DeviceState *ds)
> +{
> + PCIDevice *dev = PCI_DEVICE(ds);
> + PCII440FXState *d = I440FX_PCI_DEVICE(dev);
> + uint8_t *pci_conf = dev->config;
> +
> + pci_conf[0x59] = 0x00; /* Reset PAM setup */
> + pci_conf[0x5a] = 0x00;
> + pci_conf[0x5b] = 0x00;
> + pci_conf[0x5c] = 0x00;
> + pci_conf[0x5d] = 0x00;
> + pci_conf[0x5e] = 0x00;
> + pci_conf[0x5f] = 0x00;
> + pci_conf[0x72] = 0x02; /* And SMM */
> +
> + i440fx_update_memory_mappings(d);
> +}
> +
> static int i440fx_post_load(void *opaque, int version_id)
> {
> PCII440FXState *d = opaque;
> @@ -621,6 +639,7 @@ static void i440fx_class_init(ObjectClass *klass, void
> *data)
> dc->desc = "Host bridge";
> dc->no_user = 1;
> dc->vmsd = &vmstate_i440fx;
> + dc->reset = i440fx_reset;
> }
>
> static const TypeInfo i440fx_info = {
Cute,
Reviewed-by: Andreas Färber <afaer...@suse.de>
A minor suggestion since you seem to be preparing a v2 would be to do
I440FX_PCI_DEVICE(ds), but I don't see dev becoming unused anytime soon,
therefore moot.
Andreas
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