基于UEFI的BIOS怎么识别不同设备（SataHdd、SataCdrom、USB、BMC）
参考：UEFI_SPEC
第一种方法：
SATA设备根据EFI_ATA_DEVICE_TYPE类型来细分
ATAPI接口是SCSI和IDE总线的结合产物。该接口使用IDE接口和协议机型ATA和SCSI总线命令传输，允许使用ATAPI控制所连接的SCSI设备。
1、EFI_ATA_PASS_THRU_PROTOCOL
提供允许将ATA命令发送到附加到ATA控制器上的ATA设备的服务。基于包的命令只能通过扩展SCSI协议发送到ATAPI设备。当ATA_PASS_THRU向ATA公开一个接口，EXT_SCSI_PASS_THRU负责为同一ATA控制器上的ATAPI设备公开基于数据包的命令接口。
Status =gBS->LocateHandleBuffer (ByProtocol,&gEfiAtaPassThruProtocolGuid,NULL,&NumberHandles,&AtaPassHandles);
用LocateHandleBuffer 定位支持gEfiAtaPassThruProtocolGuid的句柄。
2、循环遍历获得的句柄，获得支持gEfiAtaPassThruProtocolGuid的接口AtaPassProtocol
for (Index = 0; Index < NumberHandles; Index++) {Status = gBS->HandleProtocol (AtaPassHandles[Index],&gEfiAtaPassThruProtocolGuid,(VOID **) &AtaPassProtocol);if (Status == EFI_SUCCESS) {Instance = ATA_PASS_THRU_PRIVATE_DATA_FROM_THIS (AtaPassProtocol);Node = GetFirstNode (&Instance->DeviceList);while (!IsNull (&Instance->DeviceList, Node)) {ATADeviceInfo = ATA_ATAPI_DEVICE_INFO_FROM_THIS (Node);Node = GetNextNode (&Instance->DeviceList, Node);}
}
3、判断条件：区分SataHdd和SataCdrom：
SataHdd：ATADeviceInfo->Type == EfiIdeHarddisk
SataCdrom：ATADeviceInfo->Type == EfiIdeCdrom；
typedef enum {
EfiIdeCdrom, /* ATAPI CDROM /
EfiIdeHarddisk, / Hard Disk /
EfiPortMultiplier, / Port Multiplier */
EfiIdeUnknown
} EFI_ATA_DEVICE_TYPE;
EFI_ATA_DEVICE_TYPE对SATA的设备类型进行细分，Cdrom,和Harddisk都接的SATA口，使用ATA类型可以进一步划分。
第二种方法：分析设备路径类型
设备路径的区分通过EFI_DEVICE_PATH_PROTOCOL的Type和SubType的值进行区分
1、EFI_DEVICE_PATH_PROTOCOL.
设备路径用于定义指向设备的编程路径。设备路径的主要目的是允许一个应用程序，例如操作系统加载程序，来确定接口正在抽象的物理设备。
可用于任何设备句柄，以获取有关物理设备或逻辑设备的通用路径/位置信息。如果句柄在逻辑上没有映射到物理设备，则该句柄可能不一定支持设备路径协议。设备路径描述了该手柄所对应的设备的位置。设备路径的大小可以由组成设备路径的结构来确定。
typedef struct {UINT8 Type; ///< 0x01 Hardware Device Path.///< 0x02 ACPI Device Path.///< 0x03 Messaging Device Path.///< 0x04 Media Device Path.///< 0x05 BIOS Boot Specification Device Path.///< 0x7F End of Hardware Device Path.UINT8 SubType; ///< Varies by Type///< 0xFF End Entire Device Path, or///< 0x01 End This Instance of a Device Path and start a new///< Device Path.UINT8 Length[2]; ///< Specific Device Path data. Type and Sub-Type define///< type of data. Size of data is included in Length.} EFI_DEVICE_PATH_PROTOCOL;
0x01 Hardware Device Path：硬盘设备路径。
0x02 ACPI Device Path. ACPI设备路径，
0x03 Messaging Device Path. SCSI设备路径：
0x04 Media Device Path. 硬盘上的分区路径
0x05 BIOS Boot Specification Device Path. 指向引导旧的操作系统的设备路径
0x7F End of Hardware Device Path. 硬件设备路径的结束。
2、主要几种设备的类型举例
需要更多类型，应查看UEFI SPEC
2.1、PCI Device Path
| Mnemonic | ByteOffset | Byte Length | Description |
|---|---|---|---|
| type | 0 | 1 | Type 1 – Hardware Device Path |
| Sub-Type | 1 | 1 | Sub-Type 1 – PCI |
| Length | 2 | 2 | Length of this structure is 6 bytes |
| 2.2、BMC Device Path | |||
| Mnemonic | ByteOffset | Byte Length | Description |
| -------- | ----- | ----- | ----- |
| type | 0 | 1 | Type 1 – Hardware Device Path |
| Sub-Type | 1 | 1 | Sub-Type 6 – BMC |
| Length | 2 | 2 | Length of this structure in bytes. Length is 13 bytes |
| 2.3、ATAPI Device Path | |||
| Mnemonic | ByteOffset | Byte Length | Description |
| -------- | ----- | ----- | ----- |
| type | 0 | 1 | Type 3 – Messaging Device Path |
| Sub-Type | 1 | 1 | Sub-Type 6 – Sub-Type 1 – ATAPI |
| Length | 2 | 2 | Length of this structure in bytes. Length is 13 bytes |
| 2.4、SCSI Device Path | |||
| Mnemonic | ByteOffset | Byte Length | Description |
| -------- | ----- | ----- | ----- |
| type | 0 | 1 | Type 3 – Messaging Device Path |
| Sub-Type | 1 | 1 | Sub-Type 6 – Sub-Type 2– SCSI |
| Length | 2 | 2 | Length of this structure in bytes. Length is 8 bytes |
| 2.5、USB Device Paths | |||
| Mnemonic | ByteOffset | Byte Length | Description |
| -------- | ----- | ----- | ----- |
| type | 0 | 1 | Type 3 – Messaging Device Path |
| Sub-Type | 1 | 1 | Sub-Type 6 – Sub-Type 5– USB |
| Length | 2 | 2 | Length of this structure in bytes. Length is 6 bytes |
| 2.6、 MAC Address Device Path | |||
| Mnemonic | ByteOffset | Byte Length | Description |
| -------- | ----- | ----- | ----- |
| type | 0 | 1 | Type 3 – Messaging Device Path |
| Sub-Type | 1 | 1 | Sub-Type 11 – MAC Address for a network interface |
| Length | 2 | 2 | Length of this structure in bytes. Length is 37 bytes |
３、判断ClassCode的值
Status = gBS->LocateHandleBuffer(ByProtocol,&gEfiPciIoProtocolGuid,NULL,&HandleArrayCount,&HandleArray);if (EFI_ERROR(Status)) {return OCPPortNum;}for (Index2=0; Index2<HandleArrayCount; Index2++){Status = gBS->HandleProtocol(HandleArray[Index2],&gEfiPciIoProtocolGuid,(VOID **)&PciIo);Status = PciIo->Pci.Read(PciIo,EfiPciIoWidthUint8,0x0B, //PCI_CLASSCODE_OFFSET1,&BaseClass);Status = PciIo->Pci.Read(PciIo,EfiPciIoWidthUint8,0x0A, //PCI_CLASSCODE_OFFSET1,&SubClass);}if(BaseClass == 0x02){// 网卡}if((BaseClass == 0x01)&&((SubClass == 0x07)||(SubClass == 0x04)){// raid卡}
