On Sun, Feb 19, 2023 at 10:54:34PM +0100, Philippe Mathieu-Daudé wrote:
+Daniel, Igor, Marcel & libvirt
On 16/2/23 16:33, Philippe Mathieu-Daudé wrote:
On 16/2/23 15:43, Bernhard Beschow wrote:
On Wed, Feb 15, 2023 at 5:20 PM Philippe Mathieu-Daudé <philmd@linaro.org <mailto:philmd@linaro.org>> wrote:
Ensure both IDE output IRQ lines are wired.
We can remove the last use of isa_get_irq(NULL).
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org <mailto:philmd@linaro.org>> --- hw/ide/piix.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-)
diff --git a/hw/ide/piix.c b/hw/ide/piix.c index 9d876dd4a7..b75a4ddcca 100644 --- a/hw/ide/piix.c +++ b/hw/ide/piix.c @@ -133,14 +133,17 @@ static bool pci_piix_init_bus(PCIIDEState *d, unsigned i, Error **errp) static const struct { int iobase; int iobase2; - int isairq; } port_info[] = { - {0x1f0, 0x3f6, 14}, - {0x170, 0x376, 15}, + {0x1f0, 0x3f6}, + {0x170, 0x376}, }; int ret;
- qemu_irq irq_out = d->irq[i] ? : isa_get_irq(NULL, port_info[i].isairq); + if (!d->irq[i]) { + error_setg(errp, "output IDE IRQ %u not connected", i); + return false; + } + ide_bus_init(&d->bus[i], sizeof(d->bus[i]), DEVICE(d), i, 2); ret = ide_init_ioport(&d->bus[i], NULL, port_info[i].iobase, port_info[i].iobase2); @@ -149,7 +152,7 @@ static bool pci_piix_init_bus(PCIIDEState *d, unsigned i, Error **errp) object_get_typename(OBJECT(d)), i); return false; } - ide_bus_init_output_irq(&d->bus[i], irq_out); + ide_bus_init_output_irq(&d->bus[i], d->irq[i]);
bmdma_init(&d->bus[i], &d->bmdma[i], d); d->bmdma[i].bus = &d->bus[i]; -- 2.38.1
This now breaks user-created piix3-ide:
qemu-system-x86_64 -M q35 -device piix3-ide
Results in:
qemu-system-x86_64: -device piix3-ide: output IDE IRQ 0 not connected
Thank you for this real-life-impossible-but-exists-in-QEMU test-case!
Do we really want to maintain this Frankenstein use case?
1/ Q35 comes with a PCIe bus on which sits a ICH chipset, which already contains a AHCI function exposing multiple IDE buses. What is the point on using an older tech?
2/ Why can we plug a PCI function on a PCIe bridge without using a pcie-pci-bridge?
FYI, this scenario is explicitly permitted by QEMU's PCIE docs, as without any bus= attr, the -device piix3-ide will end up attached to the PCI-E root complex. It thus becomes an integrated endpoint and does not support hotplug. If you want hotpluggable PCI-only device, you need to add a pcie-pci-bridge and a pci-bridge, attaching the endpoint to the latter PCE-E endpoints should always be in a pcie-root-port (or switch downstream port)
3/ Chipsets come as a whole. Software drivers might expect all PCI functions working (Linux considering each function individually is not the norm)
But the hardware really looks Frankenstein now:
(qemu) info qom-tree /machine (pc-q35-8.0-machine) /peripheral-anon (container) /device[0] (piix3-ide) /bmdma[0] (memory-region) /bmdma[1] (memory-region) /bus master container[0] (memory-region) /bus master[0] (memory-region) /ide.6 (IDE) /ide.7 (IDE) /ide[0] (memory-region) /ide[1] (memory-region) /ide[2] (memory-region) /ide[3] (memory-region) /piix-bmdma-container[0] (memory-region) /piix-bmdma[0] (memory-region) /piix-bmdma[1] (memory-region) /q35 (q35-pcihost) /unattached (container) /device[17] (ich9-ahci) /ahci-idp[0] (memory-region) /ahci[0] (memory-region) /bus master container[0] (memory-region) /bus master[0] (memory-region) /ide.0 (IDE) /ide.1 (IDE) /ide.2 (IDE) /ide.3 (IDE) /ide.4 (IDE) /ide.5 (IDE) /device[2] (ICH9-LPC) /bus master container[0] (memory-region) /bus master[0] (memory-region) /ich9-pm[0] (memory-region) /isa.0 (ISA)
I guess the diff [*] is acceptable as a kludge, but we might consider deprecating such use.
Paolo, Michael & libvirt folks, what do you think?
AFAICT, libvirt will never use '-device piix3-ide'. I vaguely recall that we discussed allowing it to enable use of > 4 IDE units, but decide it was too niche to care about. With q35 we'll just use ahci only With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|