On Fri, Jul 14, 2017 at 08:20:05PM +0200, Marc-André Lureau wrote:
> The VM coreinfo (vmcoreinfo) device is an emulated device which
> exposes a 4k memory range to the guest to store various informations
> useful to debug the guest OS. (it is greatly inspired by the VMGENID
> device implementation)
>
> This is an early-boot alternative to the qemu-ga VMDUMP_INFO event
> proposed in "[PATCH 00/21] WIP: dump: add kaslr support".
>
> A proof-of-concept kernel module:
> https://github.com/elmarco/vmgenid-test/blob/master/qemuvmci-test.c
>
> Signed-off-by: Marc-André Lureau <marcandre.lur...@redhat.com>
> Reviewed-by: Laszlo Ersek <ler...@redhat.com>
It worries me that the format of this seems completely undefined
except in the patchset cover letter.
I don't think we should merge this before it is.
> ---
> include/hw/acpi/aml-build.h | 1 +
> include/hw/acpi/vmcoreinfo.h | 37 +++++++
> hw/acpi/aml-build.c | 2 +
> hw/acpi/vmcoreinfo.c | 208
> +++++++++++++++++++++++++++++++++++++
> hw/i386/acpi-build.c | 14 +++
> default-configs/arm-softmmu.mak | 1 +
> default-configs/i386-softmmu.mak | 1 +
> default-configs/x86_64-softmmu.mak | 1 +
> docs/specs/vmcoreinfo.txt | 138 ++++++++++++++++++++++++
> hw/acpi/Makefile.objs | 1 +
> 10 files changed, 404 insertions(+)
> create mode 100644 include/hw/acpi/vmcoreinfo.h
> create mode 100644 hw/acpi/vmcoreinfo.c
> create mode 100644 docs/specs/vmcoreinfo.txt
>
> diff --git a/include/hw/acpi/aml-build.h b/include/hw/acpi/aml-build.h
> index 88d0738d76..cf781bcd34 100644
> --- a/include/hw/acpi/aml-build.h
> +++ b/include/hw/acpi/aml-build.h
> @@ -211,6 +211,7 @@ struct AcpiBuildTables {
> GArray *rsdp;
> GArray *tcpalog;
> GArray *vmgenid;
> + GArray *vmcoreinfo;
> BIOSLinker *linker;
> } AcpiBuildTables;
>
> diff --git a/include/hw/acpi/vmcoreinfo.h b/include/hw/acpi/vmcoreinfo.h
> new file mode 100644
> index 0000000000..6a73bcd1b2
> --- /dev/null
> +++ b/include/hw/acpi/vmcoreinfo.h
> @@ -0,0 +1,37 @@
> +#ifndef ACPI_VMCOREINFO_H
> +#define ACPI_VMCOREINFO_H
> +
> +#include "hw/acpi/bios-linker-loader.h"
> +#include "hw/qdev.h"
> +
> +#define VMCOREINFO_DEVICE "vmcoreinfo"
> +#define VMCOREINFO_FW_CFG_FILE "etc/vmcoreinfo"
> +#define VMCOREINFO_ADDR_FW_CFG_FILE "etc/vmcoreinfo-addr"
> +
> +/* Occupy a page of memory */
> +#define VMCOREINFO_FW_CFG_SIZE 4096
> +
> +/* allow space for OVMF SDT Header Probe Supressor */
> +#define VMCOREINFO_OFFSET sizeof(AcpiTableHeader)
> +
> +#define VMCOREINFO(obj) OBJECT_CHECK(VMCoreInfoState, (obj),
> VMCOREINFO_DEVICE)
> +
> +typedef struct VMCoreInfoState {
> + DeviceClass parent_obj;
> + uint8_t vmcoreinfo_addr_le[8]; /* Address of memory region */
> + bool write_pointer_available;
> +} VMCoreInfoState;
> +
> +/* returns NULL unless there is exactly one device */
> +static inline Object *find_vmcoreinfo_dev(void)
> +{
> + return object_resolve_path_type("", VMCOREINFO_DEVICE, NULL);
> +}
> +
> +void vmcoreinfo_build_acpi(VMCoreInfoState *vis, GArray *table_data,
> + GArray *vmci, BIOSLinker *linker);
> +void vmcoreinfo_add_fw_cfg(VMCoreInfoState *vis, FWCfgState *s, GArray
> *vmci);
> +bool vmcoreinfo_get(VMCoreInfoState *vis, uint64_t *paddr, uint32_t *size,
> + Error **errp);
> +
> +#endif
> diff --git a/hw/acpi/aml-build.c b/hw/acpi/aml-build.c
> index 36a6cc450e..47043ade4a 100644
> --- a/hw/acpi/aml-build.c
> +++ b/hw/acpi/aml-build.c
> @@ -1561,6 +1561,7 @@ void acpi_build_tables_init(AcpiBuildTables *tables)
> tables->table_data = g_array_new(false, true /* clear */, 1);
> tables->tcpalog = g_array_new(false, true /* clear */, 1);
> tables->vmgenid = g_array_new(false, true /* clear */, 1);
> + tables->vmcoreinfo = g_array_new(false, true /* clear */, 1);
> tables->linker = bios_linker_loader_init();
> }
>
> @@ -1571,6 +1572,7 @@ void acpi_build_tables_cleanup(AcpiBuildTables *tables,
> bool mfre)
> g_array_free(tables->table_data, true);
> g_array_free(tables->tcpalog, mfre);
> g_array_free(tables->vmgenid, mfre);
> + g_array_free(tables->vmcoreinfo, mfre);
> }
>
> /* Build rsdt table */
> diff --git a/hw/acpi/vmcoreinfo.c b/hw/acpi/vmcoreinfo.c
> new file mode 100644
> index 0000000000..0ea41de8d9
> --- /dev/null
> +++ b/hw/acpi/vmcoreinfo.c
> @@ -0,0 +1,208 @@
> +/*
> + * Virtual Machine coreinfo device
> + * (based on Virtual Machine Generation ID Device)
> + *
> + * Copyright (C) 2017 Red Hat, Inc.
> + * Copyright (C) 2017 Skyport Systems.
> + *
> + * Authors: Marc-André Lureau <marcandre.lur...@redhat.com>
> + * Ben Warren <b...@skyportsystems.com>
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2 or later.
> + * See the COPYING file in the top-level directory.
> + *
> + */
> +#include "qemu/osdep.h"
> +#include "hw/acpi/acpi.h"
> +#include "hw/acpi/aml-build.h"
> +#include "hw/acpi/vmcoreinfo.h"
> +#include "hw/nvram/fw_cfg.h"
> +#include "sysemu/sysemu.h"
> +#include "qapi/error.h"
> +
> +void vmcoreinfo_build_acpi(VMCoreInfoState *vis, GArray *table_data,
> + GArray *vmci, BIOSLinker *linker)
> +{
> + Aml *ssdt, *dev, *scope, *method, *addr, *if_ctx;
> + uint32_t vcia_offset;
> +
> + g_array_set_size(vmci, VMCOREINFO_FW_CFG_SIZE);
> +
> + /* Put this in a separate SSDT table */
> + ssdt = init_aml_allocator();
> +
> + /* Reserve space for header */
> + acpi_data_push(ssdt->buf, sizeof(AcpiTableHeader));
> +
> + /* Storage address */
> + vcia_offset = table_data->len +
> + build_append_named_dword(ssdt->buf, "VCIA");
> + scope = aml_scope("\\_SB");
> + dev = aml_device("VMCI");
> + aml_append(dev, aml_name_decl("_HID", aml_string("QEMUVMCI")));
> +
> + /* Simple status method to check that address is linked and non-zero */
> + method = aml_method("_STA", 0, AML_NOTSERIALIZED);
> + addr = aml_local(0);
> + aml_append(method, aml_store(aml_int(0xf), addr));
> + if_ctx = aml_if(aml_equal(aml_name("VCIA"), aml_int(0)));
> + aml_append(if_ctx, aml_store(aml_int(0), addr));
> + aml_append(method, if_ctx);
> + aml_append(method, aml_return(addr));
> + aml_append(dev, method);
> +
> + /* the ADDR method returns two 32-bit words representing the lower and
> + * upper halves of the physical address of the vmcoreinfo area
> + */
> + method = aml_method("ADDR", 0, AML_NOTSERIALIZED);
> +
> + addr = aml_local(0);
> + aml_append(method, aml_store(aml_package(2), addr));
> +
> + aml_append(method, aml_store(aml_add(aml_name("VCIA"),
> + aml_int(VMCOREINFO_OFFSET), NULL),
> + aml_index(addr, aml_int(0))));
> + aml_append(method, aml_store(aml_int(0), aml_index(addr, aml_int(1))));
> + aml_append(method, aml_return(addr));
> +
> + aml_append(dev, method);
> + aml_append(scope, dev);
> + aml_append(ssdt, scope);
> +
> + g_array_append_vals(table_data, ssdt->buf->data, ssdt->buf->len);
> +
> + /* Allocate guest memory */
> + bios_linker_loader_alloc(linker, VMCOREINFO_FW_CFG_FILE, vmci, 4096,
> + false /* page boundary, high memory */);
> +
> + /* Patch address of vmcoreinfo fw_cfg blob into the ADDR fw_cfg
> + * blob so QEMU can read the info from there. The address is
> + * expected to be < 4GB, but write 64 bits anyway.
> + * The address that is patched in is offset in order to implement
> + * the "OVMF SDT Header probe suppressor"
> + * see docs/specs/vmcoreinfo.txt for more details.
> + */
> + bios_linker_loader_write_pointer(linker,
> + VMCOREINFO_ADDR_FW_CFG_FILE, 0, sizeof(uint64_t),
> + VMCOREINFO_FW_CFG_FILE, VMCOREINFO_OFFSET);
> +
> + /* Patch address of vmcoreinfo into the AML so OSPM can retrieve
> + * and read it. Note that while we provide storage for 64 bits, only
> + * the least-signficant 32 get patched into AML.
> + */
> + bios_linker_loader_add_pointer(linker,
> + ACPI_BUILD_TABLE_FILE, vcia_offset, sizeof(uint32_t),
> + VMCOREINFO_FW_CFG_FILE, 0);
> +
> + build_header(linker, table_data,
> + (void *)(table_data->data + table_data->len - ssdt->buf->len),
> + "SSDT", ssdt->buf->len, 1, NULL, "VMCOREIN");
> + free_aml_allocator();
> +}
> +
> +void vmcoreinfo_add_fw_cfg(VMCoreInfoState *vis, FWCfgState *s, GArray *vmci)
> +{
> + /* Create a read-only fw_cfg file for vmcoreinfo allocation */
> + /* XXX: linker could learn to allocate without backing fw_cfg? */
> + fw_cfg_add_file(s, VMCOREINFO_FW_CFG_FILE, vmci->data,
> + VMCOREINFO_FW_CFG_SIZE);
> + /* Create a read-write fw_cfg file for Address */
> + fw_cfg_add_file_callback(s, VMCOREINFO_ADDR_FW_CFG_FILE, NULL, NULL,
> + vis->vmcoreinfo_addr_le,
> + ARRAY_SIZE(vis->vmcoreinfo_addr_le), false);
> +}
> +
> +bool vmcoreinfo_get(VMCoreInfoState *vis,
> + uint64_t *paddr, uint32_t *size,
> + Error **errp)
> +{
> + uint32_t vmcoreinfo_addr;
> + uint32_t version;
> +
> + assert(vis);
> + assert(paddr);
> + assert(size);
> +
> + memcpy(&vmcoreinfo_addr, vis->vmcoreinfo_addr_le,
> sizeof(vmcoreinfo_addr));
> + vmcoreinfo_addr = le32_to_cpu(vmcoreinfo_addr);
> + if (!vmcoreinfo_addr) {
> + error_setg(errp, "BIOS has not yet written the address of %s",
> + VMCOREINFO_DEVICE);
> + return false;
> + }
> +
> + cpu_physical_memory_read(vmcoreinfo_addr, &version, sizeof(version));
> + if (version != 0) {
> + error_setg(errp, "Unknown %s memory version", VMCOREINFO_DEVICE);
> + return false;
> + }
> +
> + cpu_physical_memory_read(vmcoreinfo_addr + 4, paddr, sizeof(*paddr));
> + *paddr = le64_to_cpu(*paddr);
> + cpu_physical_memory_read(vmcoreinfo_addr + 12, size, sizeof(*size));
> + *size = le32_to_cpu(*size);
> +
> + return true;
> +}
> +
> +static const VMStateDescription vmstate_vmcoreinfo = {
> + .name = "vmcoreinfo",
> + .version_id = 1,
> + .minimum_version_id = 1,
> + .fields = (VMStateField[]) {
> + VMSTATE_UINT8_ARRAY(vmcoreinfo_addr_le, VMCoreInfoState,
> sizeof(uint64_t)),
> + VMSTATE_END_OF_LIST()
> + },
> +};
> +
> +static void vmcoreinfo_handle_reset(void *opaque)
> +{
> + VMCoreInfoState *vis = VMCOREINFO(opaque);
> +
> + /* Clear the guest-allocated address when the VM resets */
> + memset(vis->vmcoreinfo_addr_le, 0, ARRAY_SIZE(vis->vmcoreinfo_addr_le));
> +}
> +
> +static void vmcoreinfo_realize(DeviceState *dev, Error **errp)
> +{
> + if (!bios_linker_loader_can_write_pointer()) {
> + error_setg(errp, "%s requires DMA write support in fw_cfg, "
> + "which this machine type does not provide",
> + VMCOREINFO_DEVICE);
> + return;
> + }
> +
> + /* Given that this function is executing, there is at least one
> VMCOREINFO
> + * device. Check if there are several.
> + */
> + if (!find_vmcoreinfo_dev()) {
> + error_setg(errp, "at most one %s device is permitted",
> + VMCOREINFO_DEVICE);
> + return;
> + }
> +
> + qemu_register_reset(vmcoreinfo_handle_reset, dev);
> +}
> +
> +static void vmcoreinfo_device_class_init(ObjectClass *klass, void *data)
> +{
> + DeviceClass *dc = DEVICE_CLASS(klass);
> +
> + dc->vmsd = &vmstate_vmcoreinfo;
> + dc->realize = vmcoreinfo_realize;
> + dc->hotpluggable = false;
> +}
> +
> +static const TypeInfo vmcoreinfo_device_info = {
> + .name = VMCOREINFO_DEVICE,
> + .parent = TYPE_DEVICE,
> + .instance_size = sizeof(VMCoreInfoState),
> + .class_init = vmcoreinfo_device_class_init,
> +};
> +
> +static void vmcoreinfo_register_types(void)
> +{
> + type_register_static(&vmcoreinfo_device_info);
> +}
> +
> +type_init(vmcoreinfo_register_types)
> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> index 6b7bade183..7ac529680e 100644
> --- a/hw/i386/acpi-build.c
> +++ b/hw/i386/acpi-build.c
> @@ -43,6 +43,7 @@
> #include "sysemu/tpm.h"
> #include "hw/acpi/tpm.h"
> #include "hw/acpi/vmgenid.h"
> +#include "hw/acpi/vmcoreinfo.h"
> #include "sysemu/tpm_backend.h"
> #include "hw/timer/mc146818rtc_regs.h"
> #include "sysemu/numa.h"
> @@ -2631,6 +2632,7 @@ void acpi_build(AcpiBuildTables *tables, MachineState
> *machine)
> GArray *tables_blob = tables->table_data;
> AcpiSlicOem slic_oem = { .id = NULL, .table_id = NULL };
> Object *vmgenid_dev;
> + Object *vmcoreinfo_dev;
>
> acpi_get_pm_info(&pm);
> acpi_get_misc_info(&misc);
> @@ -2680,6 +2682,12 @@ void acpi_build(AcpiBuildTables *tables, MachineState
> *machine)
> vmgenid_build_acpi(VMGENID(vmgenid_dev), tables_blob,
> tables->vmgenid, tables->linker);
> }
> + vmcoreinfo_dev = find_vmcoreinfo_dev();
> + if (vmcoreinfo_dev) {
> + acpi_add_table(table_offsets, tables_blob);
> + vmcoreinfo_build_acpi(VMCOREINFO(vmcoreinfo_dev), tables_blob,
> + tables->vmcoreinfo, tables->linker);
> + }
>
> if (misc.has_hpet) {
> acpi_add_table(table_offsets, tables_blob);
> @@ -2856,6 +2864,7 @@ void acpi_setup(void)
> AcpiBuildTables tables;
> AcpiBuildState *build_state;
> Object *vmgenid_dev;
> + Object *vmcoreinfo_dev;
>
> if (!pcms->fw_cfg) {
> ACPI_BUILD_DPRINTF("No fw cfg. Bailing out.\n");
> @@ -2897,6 +2906,11 @@ void acpi_setup(void)
> vmgenid_add_fw_cfg(VMGENID(vmgenid_dev), pcms->fw_cfg,
> tables.vmgenid);
> }
> + vmcoreinfo_dev = find_vmcoreinfo_dev();
> + if (vmcoreinfo_dev) {
> + vmcoreinfo_add_fw_cfg(VMCOREINFO(vmcoreinfo_dev), pcms->fw_cfg,
> + tables.vmcoreinfo);
> + }
>
> if (!pcmc->rsdp_in_ram) {
> /*
> diff --git a/default-configs/arm-softmmu.mak b/default-configs/arm-softmmu.mak
> index 93e995d318..320dd3680d 100644
> --- a/default-configs/arm-softmmu.mak
> +++ b/default-configs/arm-softmmu.mak
> @@ -120,6 +120,7 @@ CONFIG_XIO3130=y
> CONFIG_IOH3420=y
> CONFIG_I82801B11=y
> CONFIG_ACPI=y
> +CONFIG_ACPI_VMCOREINFO=y
> CONFIG_SMBIOS=y
> CONFIG_ASPEED_SOC=y
> CONFIG_GPIO_KEY=y
> diff --git a/default-configs/i386-softmmu.mak
> b/default-configs/i386-softmmu.mak
> index d2ab2f6655..df68628895 100644
> --- a/default-configs/i386-softmmu.mak
> +++ b/default-configs/i386-softmmu.mak
> @@ -59,3 +59,4 @@ CONFIG_SMBIOS=y
> CONFIG_HYPERV_TESTDEV=$(CONFIG_KVM)
> CONFIG_PXB=y
> CONFIG_ACPI_VMGENID=y
> +CONFIG_ACPI_VMCOREINFO=y
> diff --git a/default-configs/x86_64-softmmu.mak
> b/default-configs/x86_64-softmmu.mak
> index 9bde2f1c4b..e39ad5a680 100644
> --- a/default-configs/x86_64-softmmu.mak
> +++ b/default-configs/x86_64-softmmu.mak
> @@ -59,3 +59,4 @@ CONFIG_SMBIOS=y
> CONFIG_HYPERV_TESTDEV=$(CONFIG_KVM)
> CONFIG_PXB=y
> CONFIG_ACPI_VMGENID=y
> +CONFIG_ACPI_VMCOREINFO=y
> diff --git a/docs/specs/vmcoreinfo.txt b/docs/specs/vmcoreinfo.txt
> new file mode 100644
> index 0000000000..36d5a39ab1
> --- /dev/null
> +++ b/docs/specs/vmcoreinfo.txt
> @@ -0,0 +1,138 @@
> +VIRTUAL MACHINE COREINFO DEVICE
> +===============================
> +
> +Copyright (C) 2017 Red Hat, Inc.
> +
> +This work is licensed under the terms of the GNU GPL, version 2 or later.
> +See the COPYING file in the top-level directory.
> +
> +===
> +
> +The VM coreinfo (vmcoreinfo) device is an emulated device which
> +exposes a 4k memory range to the guest to store various informations
> +useful to debug the guest OS.
> +
> +QEMU Implementation
> +-------------------
> +
> +The vmcoreinfo device is put in its own ACPI descriptor table, in a
> +Secondary System Description Table, or SSDT.
> +
> +The following is a dump of the contents from a running system:
> +
> +# iasl -p ./SSDT -d /sys/firmware/acpi/tables/SSDT
> +/*
> + * Intel ACPI Component Architecture
> + * AML/ASL+ Disassembler version 20160831-64
> + * Copyright (c) 2000 - 2016 Intel Corporation
> + *
> + * Disassembling to symbolic ASL+ operators
> + *
> + * Disassembly of /sys/firmware/acpi/tables/SSDT, Mon Apr 24 15:59:53 2017
> + *
> + * Original Table Header:
> + * Signature "SSDT"
> + * Length 0x00000086 (134)
> + * Revision 0x01
> + * Checksum 0x5C
> + * OEM ID "BOCHS "
> + * OEM Table ID "VMCOREIN"
> + * OEM Revision 0x00000001 (1)
> + * Compiler ID "BXPC"
> + * Compiler Version 0x00000001 (1)
> + */
> +DefinitionBlock ("", "SSDT", 1, "BOCHS ", "VMCOREIN", 0x00000001)
> +{
> + Name (VCIA, 0x3FFFF000)
> + Scope (\_SB)
> + {
> + Device (VMCI)
> + {
> + Name (_HID, "QEMUVMCI") // _HID: Hardware ID
> + Method (_STA, 0, NotSerialized) // _STA: Status
> + {
> + Local0 = 0x0F
> + If (VCIA == Zero)
> + {
> + Local0 = Zero
> + }
> +
> + Return (Local0)
> + }
> +
> + Method (ADDR, 0, NotSerialized)
> + {
> + Local0 = Package (0x02) {}
> + Local0 [Zero] = (VCIA + 0x24)
> + Local0 [One] = Zero
> + Return (Local0)
> + }
> + }
> + }
> +}
> +
> +
> +Design Details:
> +---------------
> +
> +QEMU must be able to read the contents of the device memory,
> +specifically when starting a memory dump. In order to do this, QEMU
> +must know the address that has been allocated.
> +
> +The mechanism chosen for this memory sharing is writeable fw_cfg blobs.
> +These are data object that are visible to both QEMU and guests, and are
> +addressable as sequential files.
> +
> +More information about fw_cfg can be found in "docs/specs/fw_cfg.txt"
> +
> +Two fw_cfg blobs are used in this case:
> +
> +/etc/vmcoreinfo - used to allocate memory range, read-only to the guest
> +/etc/vmcoreinfo-addr - contains the address of the allocated range
> + - writeable by the guest
> +
> +
> +QEMU sends the following commands to the guest at startup:
> +
> +1. Allocate memory for vmcoreinfo fw_cfg blob.
> +2. Write the address of vmcoreinfo into the SSDT (VCIA ACPI variable as
> + shown above in the iasl dump). Note that this change is not propagated
> + back to QEMU.
> +3. Write the address of vmcoreinfo back to QEMU's copy of vmcoreinfo-addr
> + via the fw_cfg DMA interface.
> +
> +After step 3, QEMU is able to read the contents of vmcoreinfo.
> +
> +The value of VCIA is persisted via the VMState mechanism.
> +
> +
> +Storage Format:
> +---------------
> +
> +The content is expected to use little-endian format.
> +
> +In order to implement an OVMF "SDT Header Probe Suppressor", the contents of
> +the vmcoreinfo blob has 36 bytes of padding:
> +
> ++-----------------------------------+
> +| SSDT with OEM Table ID = VMCOREIN |
> ++-----------------------------------+
> +| ... | TOP OF PAGE
> +| VCIA dword object ----------------|-----> +---------------------------+
> +| ... | | fw-allocated array for |
> +| _STA method referring to VCIA | | "etc/vmcoreinfo" |
> +| ... | +---------------------------+
> +| ADDR method referring to VCIA | | 0: OVMF SDT Header probe |
> +| ... | | suppressor |
> ++-----------------------------------+ | 36: uint32 version field |
> + | 40: info contents |
> + | .... |
> + +---------------------------+
> + END OF PAGE
> +
> +Version 0 content:
> +
> + uint64 paddr:
> + Physical address of the Linux vmcoreinfo ELF note.
> + uint32 size:
> + Size of the vmcoreinfo ELF note.
> diff --git a/hw/acpi/Makefile.objs b/hw/acpi/Makefile.objs
> index 11c35bcb44..9623078f95 100644
> --- a/hw/acpi/Makefile.objs
> +++ b/hw/acpi/Makefile.objs
> @@ -6,6 +6,7 @@ common-obj-$(CONFIG_ACPI_MEMORY_HOTPLUG) += memory_hotplug.o
> common-obj-$(CONFIG_ACPI_CPU_HOTPLUG) += cpu.o
> common-obj-$(CONFIG_ACPI_NVDIMM) += nvdimm.o
> common-obj-$(CONFIG_ACPI_VMGENID) += vmgenid.o
> +common-obj-$(CONFIG_ACPI_VMCOREINFO) += vmcoreinfo.o
> common-obj-$(call lnot,$(CONFIG_ACPI_X86)) += acpi-stub.o
>
> common-obj-y += acpi_interface.o
> --
> 2.13.1.395.gf7b71de06
