PCIE TLP header fields

 

最近在看PCIE 资料，整理了一些笔记

       以下是TLP header 字段的总结

header filed	header location	filed Use	备注
Fmt[1:0]	bits 6:5 of byte 0	00b ：3 DW header, no data 01b ：4 DW header, no data 10b ：3 DW header, with data 11b ：4 DW header, with data	common
Type[4:0]	bits 4:0 of byte 0	0 0000 ：MRd ，Fmt[1:0] 00 or 01，Memory Read Request 0 0001 ：MRdLk ，Fmt[1:0] 00 or 01，Memory Read Request-Locked 0 0000 ：MWr ，Fmt[1:0] 10 or 11，Memory Write Request 0 0010 ：IORd ，Fmt[1:0] 00，I/O Read Request 0 0010 ：IOWr，Fmt[1:0] 10，I/O Write Request 0 0100 ：CfgRd0，Fmt[1:0] 00，Configuration Read Type 0 0 0100 ：CfgWr0，Fmt[1:0] 10，Configuration Write Type 0 0 0101 ：CfgRd1，Fmt[1:0] 00，Configuration Read Type 1 0 0101 ：CfgWr1，Fmt[1:0] 10，Configuration Write  Type 1 1 0r2r1r0：Msg，Fmt[1:0] 01，Message Request，r2r1r0 specifies the Message routing mechanism 1 0r2r1r0：MsgD，Fmt[1:0] 11，Message Request with data payload 0 1010 ：Cpl，Fmt[1:0] 00，Completion without Data– Used for I/O and Configuration Write Completions and Read Completions (I/O, Configuration, or Memory) with Completion Status other than Successful Completion. 0 1010 ：CplD，Fmt[1:0] 10，Completion with Data – Used for Memory, I/O, and Configuration Read Completions 0 1011 ：CplLk，Fmt[1:0] 00，Completion for Locked Memory Read without Data – Used only in error case 0 1011 ：CplDLk，Fmt[1:0] 10，Completion for Locked Memory Read –otherwise like CplD.	common
TC[2:0]	bits [6:4] of byte 1	Traffic Class,  differentiation of transactions into eight traffic classes	common
Attr[1:0]	bits [5:4] of byte 2	bit 5: relaxed ordering，允许某些事务（TRANSACTION）提前执行，而不是按先前的执行顺序，从而提高系统性能           0：Default Ordering，PCI Strongly Ordered Model           1：Relaxed Ordering，PCI-X Relaxed Ordering Model bit 4 ：No Snoop           0：Default，Hardware enforced cache coherency expected           1：No Snoop，Hardware enforced cache coherency not expected	common
TD	bit 7 of byte 2	1b indicates presence of TLP digest in the form of a single DW at the end of the TLP	common
EP	bit 6 of byte 2	Error Forwarding：indicates the TLP is poisoned optional	common （Write Request (Posted or Non-Posted) or a Read Completion）
Length[9:0]	bits 1:0 of byte 2 bits 7:0 of byte 3	Length of data payload in DW 00 0000 0001b：1 DW 00 0000 0010b：2 DW …                      ：... 11 1111 1111b：1023 DW 00 0000 0000b：1024 DW	common
Address[63:0]	64bits address : all bits of byte8-15 32bits address : bits of byte8-11		address routing
bus Number[7:0]	Bits 7:0 of Byte 8	specify the destination Device for the TLP	ID routing
Device Number[4:0]	Bits 7:3 of Byte 9
Function Number[2:0]	Bits 2:0 of Byte 9
Request ID[15:0]	all bits of byte 4-5	[15:8]:bus Number[7:0] [7:3] :Device Number [2:0]:Function Number	Transaction ID is included with all Requests and Completions
tag[7:0]	bits [7:0] of byte 6?	由产生请求包的器件生成的，如果请求器件需要应答，则每个Tag[7:0]是独一无二的 1.By default, only the lower 5 bits of the Tag field are used with the remaining upper 3 bits required to be all 0’s 2.If the Extended Tag Field Enable（Device Control Register ） bit  is set,the maximum is increased to 256(default 32), and the entire Tag field is used 3.For Requests which do not require Completion (Posted Requests), the value in the Tag[7:0] field is undefined and may contain any value	Request ID+Tag = Transaction ID
first  DW BE[3:0]	bits[3:0] of Byte7	[0]: affected data Byte 0 [1]: affected data Byte 1 [2]: affected data Byte 2 [3]: affected data Byte 3	Memory, I/O, and Configuration Requests
Last DW BE[3:0]	bits[7:4] of Byte7	[0]: affected data Byte N-4 [1]: affected data Byte N-3 [2]: affected data Byte N-2 [3]: affected data Byte N-1 Assuming the data referenced is N bytes in length (Byte 0 to Byte N-1)
Completer ID[15:0]	all bits of byte 4-5	Identifies the Completer [15:8]:bus Number[7:0] [7:3] :Device Number [2:0]:Function Number	Completion
Completion Status[2:0]	bit 7:5 of byte6	Indicates the status for a Completion 000b: Successful Completion (SC),请求（Request）被正确的处理 001b: Unsupported Request (UR),表示请求是非法的或者不能被Completer所识别的 010b: Configuration Request Retry Status (CRS),Completer暂时不能响应的配置请求，需要Requester稍后再次尝试 100b: Completer Abort (CA),Completer可以响应该请求，但是却发生了其他的错误，该错误是Uncorrectable Error all others: Reserved	Completion
BCM		Byte Count Modified must not set by PCI Express Completers, and may only be set by PCI-X completers	Completion
Byte Count[11:0]	bit 3:0 of byte6 bit 7:0 of byte7	The remaining byte count for Request 0000 0000 0000b :  4096 bytes 0000 0000 0001b : 1 byte …… 1111 1111 1111b : 4095 bytes	Completion
tag[7:0]	bit 7:0 of byte10	in combination with the Requester ID field, corresponds to the Transaction ID	Completion
Lower Address[6:0]	bit 6:0 of byte11	lower byte address for starting byte of Completion	Completion
仅针对pcie 1.0a，不同的版本会有所不同