acpi table解析过程分析
acpi表结构大概是这样的
知道了表的大概结构我问来分析的解析的过程
解析的入口函数为acpi_tb_parse_root_table 函数
/*******************************************************************************
*
* FUNCTION: acpi_tb_parse_root_table
*
* PARAMETERS: rsdp - Pointer to the RSDP
*
* RETURN: Status
*
* DESCRIPTION: This function is called to parse the Root System Description
* Table (RSDT or XSDT)
*
* NOTE: Tables are mapped (not copied) for efficiency. The FACS must
* be mapped and cannot be copied because it contains the actual
* memory location of the ACPI Global Lock.
*
******************************************************************************/
acpi_status __init acpi_tb_parse_root_table(acpi_physical_address rsdp_address)
{
struct acpi_table_rsdp *rsdp;
u32 table_entry_size;
u32 i;
u32 table_count;
struct acpi_table_header *table;
acpi_physical_address address;
u32 length;
u8 *table_entry;
acpi_status status;
u32 table_index;
ACPI_FUNCTION_TRACE(tb_parse_root_table);
/* Map the entire RSDP and extract the address of the RSDT or XSDT */
rsdp = acpi_os_map_memory(rsdp_address, sizeof(struct acpi_table_rsdp));
if (!rsdp) {
return_ACPI_STATUS(AE_NO_MEMORY);
}
acpi_tb_print_table_header(rsdp_address,
ACPI_CAST_PTR(struct acpi_table_header,
rsdp));
/* Use XSDT if present and not overridden. Otherwise, use RSDT */
if ((rsdp->revision > 1) &&
rsdp->xsdt_physical_address && !acpi_gbl_do_not_use_xsdt) {
/*
* RSDP contains an XSDT (64-bit physical addresses). We must use
* the XSDT if the revision is > 1 and the XSDT pointer is present,
* as per the ACPI specification.
*/
address = (acpi_physical_address) rsdp->xsdt_physical_address;
table_entry_size = ACPI_XSDT_ENTRY_SIZE;
} else {
/* Root table is an RSDT (32-bit physical addresses) */
address = (acpi_physical_address) rsdp->rsdt_physical_address;
table_entry_size = ACPI_RSDT_ENTRY_SIZE;
}
/*
* It is not possible to map more than one entry in some environments,
* so unmap the RSDP here before mapping other tables
*/
acpi_os_unmap_memory(rsdp, sizeof(struct acpi_table_rsdp));
/* Map the RSDT/XSDT table header to get the full table length */
table = acpi_os_map_memory(address, sizeof(struct acpi_table_header));
if (!table) {
return_ACPI_STATUS(AE_NO_MEMORY);
}
acpi_tb_print_table_header(address, table);
/*
* Validate length of the table, and map entire table.
* Minimum length table must contain at least one entry.
*/
length = table->length;
acpi_os_unmap_memory(table, sizeof(struct acpi_table_header));
if (length < (sizeof(struct acpi_table_header) + table_entry_size)) {
ACPI_BIOS_ERROR((AE_INFO,
"Invalid table length 0x%X in RSDT/XSDT",
length));
return_ACPI_STATUS(AE_INVALID_TABLE_LENGTH);
}
table = acpi_os_map_memory(address, length);
if (!table) {
return_ACPI_STATUS(AE_NO_MEMORY);
}
/* Validate the root table checksum */
status = acpi_tb_verify_checksum(table, length);
if (ACPI_FAILURE(status)) {
acpi_os_unmap_memory(table, length);
return_ACPI_STATUS(status);
}
/* Get the number of entries and pointer to first entry */
table_count = (u32)((table->length - sizeof(struct acpi_table_header)) /
table_entry_size);
table_entry = ACPI_ADD_PTR(u8, table, sizeof(struct acpi_table_header));
/*
* First three entries in the table array are reserved for the DSDT
* and 32bit/64bit FACS, which are not actually present in the
* RSDT/XSDT - they come from the FADT
*/
acpi_gbl_root_table_list.current_table_count = 3;
/* Initialize the root table array from the RSDT/XSDT */
for (i = 0; i < table_count; i++) {
/* Get the table physical address (32-bit for RSDT, 64-bit for XSDT) */
address =
acpi_tb_get_root_table_entry(table_entry, table_entry_size);
/* Skip NULL entries in RSDT/XSDT */
if (!address) {
goto next_table;
}
status = acpi_tb_install_standard_table(address,
ACPI_TABLE_ORIGIN_INTERNAL_PHYSICAL,
FALSE, TRUE,
&table_index);
if (ACPI_SUCCESS(status) &&
ACPI_COMPARE_NAME(&acpi_gbl_root_table_list.
tables[table_index].signature,
ACPI_SIG_FADT)) {
acpi_tb_parse_fadt(table_index);
}
next_table:
table_entry += table_entry_size;
}
acpi_os_unmap_memory(table, length);
return_ACPI_STATUS(AE_OK);
}
首先注释上说acpi表为了高效使用map映射，而FACS必须使用映射因为这段内存中存在全局锁
1 rsdp = acpi_os_map_memory(rsdp_address, sizeof(struct acpi_table_rsdp));
映射到虚拟地址RSDP
2acpi_tb_print_table_header 打印表头
表头结构如下，注意表头是直接从rsdp转换得到的
/*******************************************************************************
*
* Master ACPI Table Header. This common header is used by all ACPI tables
* except the RSDP and FACS.
*
******************************************************************************/
struct acpi_table_header {
char signature[ACPI_NAME_SIZE]; /* ASCII table signature */
u32 length; /* Length of table in bytes, including this header */
u8 revision; /* ACPI Specification minor version number */
u8 checksum; /* To make sum of entire table == 0 */
char oem_id[ACPI_OEM_ID_SIZE]; /* ASCII OEM identification */
char oem_table_id[ACPI_OEM_TABLE_ID_SIZE]; /* ASCII OEM table identification */
u32 oem_revision; /* OEM revision number */
char asl_compiler_id[ACPI_NAME_SIZE]; /* ASCII ASL compiler vendor ID */
u32 asl_compiler_revision; /* ASL compiler version */
};
第一项signature是表的签名
length为表的长度
revision 版本
checksum 校验值
oem_id 厂商id
oem_table_id table的id
oem_revision厂商版本
asl_compiler_id 编译器id
asl_compiler_revision 编译器版本
编译是为解释acpi操作语言ASL的编译器
3 根据版本选择使用xsdt还是rsdt， revision>1并且存在xsdt的情况必须使用XSDT
XSDT表全称Extended Root System Description Table,它的作用于RSDT一样，区别在于两者包含的指针地址一个是32位的，一个是64位的。XSDT表结构如下
typedef struct {
EFI_ACPI_DESCRIPTION_HEADER Header;
UINT64 Entry;
RSDT结构如下
typedef struct {
EFI_ACPI_DESCRIPTION_HEADER Header;
UINT32 Entry;
}
4 找到要具体使用的RSDT/XSDT就可以进行解析了，首先解除RSDP的映射，
然后映射RSDT/XSDT表头，通过表头验证表长度是否正确，如果正确再
映射整张表
5 验证表校验和
6 处表头后为entry，获取entry个数，able_count = (u32)((table->length - sizeof(struct acpi_table_header)) /table_entry_size)
7 acpi_gbl_root_table_list.current_table_count = 3 该值设置为3的理由是保留前三项用于存放DSDT 和 FACS，这两个表不是从RSDT和XSDT中获取的，而是从FADT中得到的
8 按照计算好的表项个数去遍历RSDT/XSDT
acpi_tb_get_root_table_entry函数用于获取一个entry
acpi_tb_install_standard_table用于安装标准table
如果table是FADT 则使用acpi_tb_parse_fadt函数去解析DSDT 和 FACS
下面具体分析下acpi_tb_get_root_table_entry 函数，acpi_tb_install_standard_table和acpi_tb_parse_fadt
acpi_tb_get_root_table_entry用于从RSDT/XSDT中解析子table
注意RSDT/XSDT的entry变量描述的就是子table的物理地址
/*******************************************************************************
*
* FUNCTION: acpi_tb_get_root_table_entry
*
* PARAMETERS: table_entry - Pointer to the RSDT/XSDT table entry
* table_entry_size - sizeof 32 or 64 (RSDT or XSDT)
*
* RETURN: Physical address extracted from the root table
*
* DESCRIPTION: Get one root table entry. Handles 32-bit and 64-bit cases on
* both 32-bit and 64-bit platforms
*
* NOTE: acpi_physical_address is 32-bit on 32-bit platforms, 64-bit on
* 64-bit platforms.
*
******************************************************************************/
static acpi_physical_address
acpi_tb_get_root_table_entry(u8 *table_entry, u32 table_entry_size)
{
u64 address64;
/*
* Get the table physical address (32-bit for RSDT, 64-bit for XSDT):
* Note: Addresses are 32-bit aligned (not 64) in both RSDT and XSDT
*/
if (table_entry_size == ACPI_RSDT_ENTRY_SIZE) {
/*
* 32-bit platform, RSDT: Return 32-bit table entry
* 64-bit platform, RSDT: Expand 32-bit to 64-bit and return
*/
return ((acpi_physical_address)
(*ACPI_CAST_PTR(u32, table_entry)));
} else {
/*
* 32-bit platform, XSDT: Truncate 64-bit to 32-bit and return
* 64-bit platform, XSDT: Move (unaligned) 64-bit to local,
* return 64-bit
*/
ACPI_MOVE_64_TO_64(&address64, table_entry);
#if ACPI_MACHINE_WIDTH == 32
if (address64 > ACPI_UINT32_MAX) {
/* Will truncate 64-bit address to 32 bits, issue warning */
ACPI_BIOS_WARNING((AE_INFO,
"64-bit Physical Address in XSDT is too large (0x%8.8X%8.8X),"
" truncating",
ACPI_FORMAT_UINT64(address64)));
}
#endif
return ((acpi_physical_address) (address64));
}
}
其实很简单，就是按照RSDT(32位entry) 或者 XDDT(64位entry) 转换一下。
acpi_tb_install_standard_table函数用于安装前面解析到的table entry指向的table
/*******************************************************************************
*
* FUNCTION: acpi_tb_install_standard_table
*
* PARAMETERS: address - Address of the table (might be a virtual
* address depending on the table_flags)
* flags - Flags for the table
* reload - Whether reload should be performed
* override - Whether override should be performed
* table_index - Where the table index is returned
*
* RETURN: Status
*
* DESCRIPTION: This function is called to install an ACPI table that is
* neither DSDT nor FACS (a "standard" table.)
* When this function is called by "Load" or "LoadTable" opcodes,
* or by acpi_load_table() API, the "Reload" parameter is set.
* After sucessfully returning from this function, table is
* "INSTALLED" but not "VALIDATED".
*
******************************************************************************/
acpi_status
acpi_tb_install_standard_table(acpi_physical_address address,
u8 flags,
u8 reload, u8 override, u32 *table_index)
{
u32 i;
acpi_status status = AE_OK;
struct acpi_table_desc new_table_desc;
ACPI_FUNCTION_TRACE(tb_install_standard_table);
/* Acquire a temporary table descriptor for validation */
status = acpi_tb_acquire_temp_table(&new_table_desc, address, flags);
if (ACPI_FAILURE(status)) {
ACPI_ERROR((AE_INFO,
"Could not acquire table length at %8.8X%8.8X",
ACPI_FORMAT_UINT64(address))); return_ACPI_STATUS(status);
}
/*
* Optionally do not load any SSDTs from the RSDT/XSDT. This can
* be useful for debugging ACPI problems on some machines.
*/
if (!reload &&
acpi_gbl_disable_ssdt_table_install &&
ACPI_COMPARE_NAME(&new_table_desc.signature, ACPI_SIG_SSDT)) {
ACPI_INFO((AE_INFO,
"Ignoring installation of %4.4s at %8.8X%8.8X",
new_table_desc.signature.ascii,
ACPI_FORMAT_UINT64(address)));
goto release_and_exit;
}
/* Validate and verify a table before installation */
status = acpi_tb_verify_temp_table(&new_table_desc, NULL);
if (ACPI_FAILURE(status)) {
goto release_and_exit;
}
if (reload) {
/*
* Validate the incoming table signature.
*
* 1) Originally, we checked the table signature for "SSDT" or "PSDT".
* 2) We added support for OEMx tables, signature "OEM".
* 3) Valid tables were encountered with a null signature, so we just
* gave up on validating the signature, (05/2008).
* 4) We encountered non-AML tables such as the MADT, which caused
* interpreter errors and kernel faults. So now, we once again allow
* only "SSDT", "OEMx", and now, also a null signature. (05/2011).
*/
if ((new_table_desc.signature.ascii[0] != 0x00) &&
(!ACPI_COMPARE_NAME
(&new_table_desc.signature, ACPI_SIG_SSDT))
&& (ACPI_STRNCMP(new_table_desc.signature.ascii, "OEM", 3)))
{
ACPI_BIOS_ERROR((AE_INFO,
"Table has invalid signature [%4.4s] (0x%8.8X), "
"must be SSDT or OEMx",
acpi_ut_valid_acpi_name(new_table_desc.
signature.
ascii) ?
new_table_desc.signature.
ascii : "????",
new_table_desc.signature.integer));
status = AE_BAD_SIGNATURE;
goto release_and_exit;
}
/* Check if table is already registered */
for (i = 0; i < acpi_gbl_root_table_list.current_table_count;
++i) {
/*
* Check for a table match on the entire table length,
* not just the header.
*/
if (!acpi_tb_compare_tables(&new_table_desc, i)) {
continue;
}
/*
* Note: the current mechanism does not unregister a table if it is
* dynamically unloaded. The related namespace entries are deleted,
* but the table remains in the root table list.
*
* The assumption here is that the number of different tables that
* will be loaded is actually small, and there is minimal overhead
* in just keeping the table in case it is needed again.
*
* If this assumption changes in the future (perhaps on large
* machines with many table load/unload operations), tables will
* need to be unregistered when they are unloaded, and slots in the
* root table list should be reused when empty.
*/
if (acpi_gbl_root_table_list.tables[i].
flags & ACPI_TABLE_IS_LOADED) {
/* Table is still loaded, this is an error */
status = AE_ALREADY_EXISTS;
goto release_and_exit;
} else {
/*
* Table was unloaded, allow it to be reloaded.
* As we are going to return AE_OK to the caller, we should
* take the responsibility of freeing the input descriptor.
* Refill the input descriptor to ensure
* acpi_tb_install_table_with_override() can be called again to
* indicate the re-installation.
*/
acpi_tb_uninstall_table(&new_table_desc);
*table_index = i;
return_ACPI_STATUS(AE_OK);
}
}
}
/* Add the table to the global root table list */
status = acpi_tb_get_next_root_index(&i);
if (ACPI_FAILURE(status)) {
goto release_and_exit;
}
*table_index = i;
acpi_tb_install_table_with_override(i, &new_table_desc, override);
release_and_exit:
/* Release the temporary table descriptor */
acpi_tb_release_temp_table(&new_table_desc);
return_ACPI_STATUS(status);
}
这是一个比较凶恶的函数，代码很长
1 acpi_tb_acquire_temp_table 用于创建一个acpi_table_desc结构，acpi_table_desc定义如下
struct acpi_table_desc {
acpi_physical_address address;
struct acpi_table_header *pointer;
u32 length; /* Length fixed at 32 bits (fixed in table header) */
union acpi_name_union signature;
acpi_owner_id owner_id;
u8 flags;
};
主要描述了table的物理地址， table头地址和table长度，签名以及标志
2 acpi_tb_verify_temp_table 验证table是否可用，主要验证包括签名，check sum，长度等信息
3 reload表示重新加载，要先卸载原来的再加载当前的
4 acpi_tb_install_table_with_override 安装
/*******************************************************************************
*
* FUNCTION: acpi_tb_install_table_with_override
*
* PARAMETERS: table_index - Index into root table array
* new_table_desc - New table descriptor to install
* override - Whether override should be performed
*
* RETURN: None
*
* DESCRIPTION: Install an ACPI table into the global data structure. The
* table override mechanism is called to allow the host
* OS to replace any table before it is installed in the root
* table array.
*
******************************************************************************/
void
acpi_tb_install_table_with_override(u32 table_index,
struct acpi_table_desc *new_table_desc,
u8 override)
{
if (table_index >= acpi_gbl_root_table_list.current_table_count) {
return;
}
/*
* ACPI Table Override:
*
* Before we install the table, let the host OS override it with a new
* one if desired. Any table within the RSDT/XSDT can be replaced,
* including the DSDT which is pointed to by the FADT.
*/
if (override) {
acpi_tb_override_table(new_table_desc);
}
acpi_tb_init_table_descriptor(&acpi_gbl_root_table_list.
tables[table_index],
new_table_desc->address,
new_table_desc->flags,
new_table_desc->pointer);
acpi_tb_print_table_header(new_table_desc->address,
new_table_desc->pointer);
/* Set the global integer width (based upon revision of the DSDT) */
if (table_index == ACPI_TABLE_INDEX_DSDT) {
acpi_ut_set_integer_width(new_table_desc->pointer->revision);
}
}
1 如果覆盖参数为真，则用新表覆盖老表acpi_tb_override_table
2 acpi_tb_init_table_descriptor 初始化表,注意这里的参数是&acpi_gbl_root_table_list.
tables[table_index]， 也就是把table_descriptor 安装到acpi_gbl_root_table_list.tables数组就算安装完成了
acpi_tb_parse_fadt函数去解析DSDT 和 FACS
/*******************************************************************************
*
* FUNCTION: acpi_tb_parse_fadt
*
* PARAMETERS: table_index - Index for the FADT
*
* RETURN: None
*
* DESCRIPTION: Initialize the FADT, DSDT and FACS tables
* (FADT contains the addresses of the DSDT and FACS)
*
******************************************************************************/
void acpi_tb_parse_fadt(u32 table_index)
{
u32 length;
struct acpi_table_header *table;
/*
* The FADT has multiple versions with different lengths,
* and it contains pointers to both the DSDT and FACS tables.
*
* Get a local copy of the FADT and convert it to a common format
* Map entire FADT, assumed to be smaller than one page.
*/
length = acpi_gbl_root_table_list.tables[table_index].length;
table =
acpi_os_map_memory(acpi_gbl_root_table_list.tables[table_index].
address, length);
if (!table) {
return;
}
/*
* Validate the FADT checksum before we copy the table. Ignore
* checksum error as we want to try to get the DSDT and FACS.
*/
(void)acpi_tb_verify_checksum(table, length);
/* Create a local copy of the FADT in common ACPI 2.0+ format */
acpi_tb_create_local_fadt(table, length);
/* All done with the real FADT, unmap it */
acpi_os_unmap_memory(table, length);
/* Obtain the DSDT and FACS tables via their addresses within the FADT */
acpi_tb_install_fixed_table((acpi_physical_address) acpi_gbl_FADT.Xdsdt,
ACPI_SIG_DSDT, ACPI_TABLE_INDEX_DSDT);
/* If Hardware Reduced flag is set, there is no FACS */
if (!acpi_gbl_reduced_hardware) {
if (acpi_gbl_FADT.facs) {
acpi_tb_install_fixed_table((acpi_physical_address)
acpi_gbl_FADT.facs,
ACPI_SIG_FACS,
ACPI_TABLE_INDEX_FACS);
}
if (acpi_gbl_FADT.Xfacs) {
acpi_tb_install_fixed_table((acpi_physical_address)
acpi_gbl_FADT.Xfacs,
ACPI_SIG_FACS,
ACPI_TABLE_INDEX_X_FACS);
}
}
}
函数用于初始化FADT, DSDT and FACS , FADT 包含DSDT和FACS 。
这里FADT已经通过acpi_tb_install_standard_table 函数安装到了acpi_gbl_root_table_list.tables数组中
1 映射FADT，因为要从这个table中找到DSDT 和 FACS
2 校验该table
3 转换FDAT为标准格式，主要是设置全局变量 struct acpi_table_fadt acpi_gbl_FADT
4 安装 DSDT
5 安装facs和Xfacs