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Re: [Qemu-devel] [PATCH 2/2] pc: acpi-build: make linker & RSDP tables d
From: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-devel] [PATCH 2/2] pc: acpi-build: make linker & RSDP tables dynamic |
Date: |
Wed, 10 Dec 2014 20:28:01 +0200 |
On Wed, Dec 10, 2014 at 06:39:49PM +0100, Igor Mammedov wrote:
> On Wed, 10 Dec 2014 19:13:59 +0200
> "Michael S. Tsirkin" <address@hidden> wrote:
>
> > On Wed, Dec 10, 2014 at 05:45:58PM +0100, Igor Mammedov wrote:
> > > On Wed, 10 Dec 2014 18:24:24 +0200
> > > "Michael S. Tsirkin" <address@hidden> wrote:
> > >
> > > > On Wed, Dec 10, 2014 at 04:06:56PM +0000, Igor Mammedov wrote:
> > > > > linker and RSDP tables are build only once, so if later
> > > > > during rebuild sizes of other ACPI tables change
> > > > > pointers will be patched incorrectly due to wrong
> > > > > offsets.
> > > > >
> > > > > To fix it rebuild linker and RSDP tables along with
> > > > > the rest of ACPI tables so that they would have correct
> > > > > offsets.
> > > > >
> > > > > Here is a simple reproducer:
> > > > > 1: hotplug bridge using command:
> > > > > device_add pci-bridge,chassis_nr=1
> > > > > 2: reset system from monitor:
> > > > > system_reset
> > > > >
> > > > > As result pointers to ACPI tables are not correct
> > > > > and guest can't read/parse ACPI tables.
> > > > > Windows guests just refuse to boot and
> > > > > Linux guests are more resilient and try to boot without
> > > > > ACPI, sometimes successfully.
> > > > >
> > > > > PS:
> > > > > keep brokenness in 2.2 and older machine types for the sake
> > > > > of migration
> > > > >
> > > > > Signed-off-by: Igor Mammedov <address@hidden>
> > > >
> > > > I'd like to fix 2.2 as well.
> > > that's easy,
> > > has_imutable_rsdp = true
> > > should be moved into
> > > pc_compat_2_1()
> > >
> > > >
> > > > Why does adding bridge in this way cause tables to
> > > > be resized?
> > > > I think this is a root-cause that should be fixed.
> > > That's because there wasn't any bridge described in tables
> > > on startup, but after hotplug and reset tables are rebuild
> > > which pickups hotplugged bridge and its secondary PCI bus.
> > >
> > > This behavior seems sane, I'd expect bare-metal behave
> > > the same way.
> >
> > For a simple fix, we can skip bridges added by hotplug -
> > treat them as regular devices.
> >
> > It defintely seems nicer - at least for old machine types -
> > than "keep brokenness".
> >
> > I think the following should do the trcik, but it's completely
> > untested.
> > Could you pls try?
> >
> >
> > diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> > index b37a397..039776d 100644
> > --- a/hw/i386/acpi-build.c
> > +++ b/hw/i386/acpi-build.c
> > @@ -844,7 +844,8 @@ static void build_pci_bus_end(PCIBus *bus, void
> > *bus_state)
> > * Skip bridge subtree creation if bridge hotplug is disabled
> > * to make acpi tables compatible with legacy machine types.
> > */
> > - if (!child->pcihp_bridge_en && bus->parent_dev) {
> > + if (bus->parent_dev && (!child->pcihp_bridge_en ||
> > + !DEVICE(bus->parent_dev)->hotplugged)) {
> > return;
> > }
> What will happen if
> hotplug may bridges in
> QEMU-fixed^^ -M 2.1
> migrate to target:
> QEMU-2.1 -M 2.1 + hotplugged on sourcebridges on CLI
>
> My guess it may fail due to ACPI blob size difference.
Yes it might if we are unlucky and cross a 64 k boundary.
The robust fix is still to resize ROMs on receive.
We'll also put this patch on a stable branch.
--
MST
- [Qemu-devel] [PATCH 0/2] pc: fix ACPI tables corruption after bridge hotplug, Igor Mammedov, 2014/12/10
- [Qemu-devel] [PATCH 2/2] pc: acpi-build: make linker & RSDP tables dynamic, Igor Mammedov, 2014/12/10
- Re: [Qemu-devel] [PATCH 2/2] pc: acpi-build: make linker & RSDP tables dynamic, Michael S. Tsirkin, 2014/12/10
- Re: [Qemu-devel] [PATCH 2/2] pc: acpi-build: make linker & RSDP tables dynamic, Igor Mammedov, 2014/12/10
- Re: [Qemu-devel] [PATCH 2/2] pc: acpi-build: make linker & RSDP tables dynamic, Michael S. Tsirkin, 2014/12/10
- Re: [Qemu-devel] [PATCH 2/2] pc: acpi-build: make linker & RSDP tables dynamic, Igor Mammedov, 2014/12/10
- Re: [Qemu-devel] [PATCH 2/2] pc: acpi-build: make linker & RSDP tables dynamic,
Michael S. Tsirkin <=
- Re: [Qemu-devel] [PATCH 2/2] pc: acpi-build: make linker & RSDP tables dynamic, Igor Mammedov, 2014/12/10
- Re: [Qemu-devel] [PATCH 2/2] pc: acpi-build: make linker & RSDP tables dynamic, Michael S. Tsirkin, 2014/12/10
- Re: [Qemu-devel] [PATCH 2/2] pc: acpi-build: make linker & RSDP tables dynamic, Igor Mammedov, 2014/12/11
[Qemu-devel] [PATCH 1/2] pc: Add pc-[i440fx|q35]-2.3 machine type and pc_compat_2_2() function, Igor Mammedov, 2014/12/10