The patch set consists of two parts:
patches 1-4: introduce new feature
'acpi-pci-hotplug-with-bridge-support' on Q35
patches 5-7: make the feature default along with changes in ACPI tables
This way maintainers can decide which way to choose without breaking
the patch set.
With the feature disabled Q35 falls back to the native hot-plug.
Pros
* no racy behavior during boot (see 110c477c2ed)
* eject is possible - according to PCIe spec, attention button
press should lead to power off, and then the adapter should be
removed manually. As there is no power down state exists in QEMU,
we cannot distinguish between an eject and a power down
request.
* no delay during deleting - after the actual power off software
must wait at least 1 second before indicating about it. This case
is quite important for users, it even has its own bug:
https://bugzilla.redhat.com/show_bug.cgi?id=1594168
* no timer-based behavior - in addition to the previous example,
the attention button has a 5-second waiting period, during which
the operation can be canceled with a second press. While this
looks fine for manual button control, automation will result in
the need to queue or drop events, and the software receiving
events in all sort of unspecified combinations of attention/power
indicator states, which is racy and uppredictable.
* fixes:
* https://bugzilla.redhat.com/show_bug.cgi?id=1752465
* https://bugzilla.redhat.com/show_bug.cgi?id=1690256
Cons:
* lose per-port control over hot-plug (can be resolved)
* no access to possible features presented in slot capabilities
(this is only surprise removal AFAIK)
v3:
* drop change of _OSC to allow SHPC on hotplugged bridges
* use 'acpi-root-pci-hotplug'
* add migration states [Igor]
* minor style changes
v2:
* new ioport range for acpiphp [Gerd]
* drop find_pci_host() [Igor]
* explain magic numbers in _OSC [Igor]
* drop build_q35_pci_hotplug() wrapper [Igor]
Julia Suvorova (7):
hw/acpi/pcihp: Enhance acpi_pcihp_disable_root_bus() to support Q35
hw/i386/acpi-build: Add ACPI PCI hot-plug methods to Q35
hw/pci/pcie: Do not initialize slot capability if acpihp is used
hw/acpi/ich9: Enable ACPI PCI hot-plug
bios-tables-test: Allow changes in DSDT ACPI tables
hw/acpi/ich9: Set ACPI PCI hot-plug as default
bios-tables-test: Update golden binaries
hw/i386/acpi-build.h | 7 ++++
include/hw/acpi/ich9.h | 5 +++
include/hw/acpi/pcihp.h | 3 +-
hw/acpi/ich9.c | 67 ++++++++++++++++++++++++++++++
hw/acpi/pcihp.c | 16 ++++---
hw/acpi/piix4.c | 4 +-
hw/i386/acpi-build.c | 31 ++++++++------
hw/i386/pc.c | 1 +
hw/pci/pcie.c | 16 +++++++
tests/data/acpi/q35/DSDT | Bin 7678 -> 7950 bytes
tests/data/acpi/q35/DSDT.acpihmat | Bin 9002 -> 9274 bytes
tests/data/acpi/q35/DSDT.bridge | Bin 7695 -> 9865 bytes
tests/data/acpi/q35/DSDT.cphp | Bin 8141 -> 8413 bytes
tests/data/acpi/q35/DSDT.dimmpxm | Bin 9331 -> 9603 bytes
tests/data/acpi/q35/DSDT.ipmibt | Bin 7753 -> 8025 bytes
tests/data/acpi/q35/DSDT.memhp | Bin 9037 -> 9309 bytes
tests/data/acpi/q35/DSDT.mmio64 | Bin 8808 -> 9080 bytes
tests/data/acpi/q35/DSDT.numamem | Bin 7684 -> 7956 bytes
tests/data/acpi/q35/DSDT.tis | Bin 8283 -> 8555 bytes
19 files changed, 129 insertions(+), 21 deletions(-)
--
2.25.4
