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q35: acpi: do not create dummy MCFG table

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Dummy table (with signature "QEMU") creation came from original SeaBIOS
codebase. And QEMU would have to keep it around if there were Q35 machine
that depended on keeping ACPI tables blob constant size. Luckily there
were no versioned Q35 machine types before commit:
  (since 2.3) a1666142db acpi-build: make ROMs RAM blocks resizeable
which obsoleted need to keep ACPI tables blob the same size on source/destination.

Considering the 1st versioned machine is pc-q35-2.4, the dummy table
is not really necessary and it's safe to drop it without breaking
cross version migration in both directions unconditionally.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Message-Id: <1554822037-329838-1-git-send-email-imammedo@redhat.com>
Reviewed-by: Wei Yang <richardw.yang@linux.intel.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Igor Mammedov 2019-04-09 17:00:37 +02:00 committed by Michael S. Tsirkin
parent 03459ea3b3
commit fe4970ad46
1 changed files with 4 additions and 14 deletions
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18
hw/i386/acpi-build.c
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@ -2413,7 +2413,6 @@ static void
build_mcfg_q35(GArray *table_data, BIOSLinker *linker, AcpiMcfgInfo *info)
{
AcpiTableMcfg *mcfg;
const char *sig;
int len = sizeof(*mcfg) + 1 * sizeof(mcfg->allocation[0]);
mcfg = acpi_data_push(table_data, len);
@ -2423,19 +2422,7 @@ build_mcfg_q35(GArray *table_data, BIOSLinker *linker, AcpiMcfgInfo *info)
mcfg->allocation[0].start_bus_number = 0;
mcfg->allocation[0].end_bus_number = PCIE_MMCFG_BUS(info->mcfg_size - 1);
/* MCFG is used for ECAM which can be enabled or disabled by guest.
* To avoid table size changes (which create migration issues),
* always create the table even if there are no allocations,
* but set the signature to a reserved value in this case.
* ACPI spec requires OSPMs to ignore such tables.
*/
if (info->mcfg_base == PCIE_BASE_ADDR_UNMAPPED) {
/* Reserved signature: ignored by OSPM */
sig = "QEMU";
} else {
sig = "MCFG";
}
build_header(linker, table_data, (void *)mcfg, sig, len, 1, NULL, NULL);
build_header(linker, table_data, (void *)mcfg, "MCFG", len, 1, NULL, NULL);
}
/*
@ -2604,6 +2591,9 @@ static bool acpi_get_mcfg(AcpiMcfgInfo *mcfg)
}
mcfg->mcfg_base = qnum_get_uint(qobject_to(QNum, o));
qobject_unref(o);
if (mcfg->mcfg_base == PCIE_BASE_ADDR_UNMAPPED) {
return false;
}
o = object_property_get_qobject(pci_host, PCIE_HOST_MCFG_SIZE, NULL);
assert(o);