https://www.intel.com/content/dam/s...s/server/sr4850hw4/sb/se8501hw4_board_tps.pdf
bottom of page 108.
PEI core. The PEI is where first probe of memory timings happen generally.
or here
https://www.intel.com/content/dam/s...server-products/S7200AP-APR-Service-Guide.pdf
starting around page 87
PEI Phase
10 - PEI Core is started
11 - Pre-memory CPU initialization is started
12 - Pre-memory CPU initialization (CPU module specific)
13 - Pre-memory CPU initialization (CPU module specific)
14 - Pre-memory CPU initialization (CPU module specific)
15 - Pre-memory System Agent initialization is started
16 - Pre-Memory System Agent initialization (System Agent module specific)
17 - Pre-Memory System Agent initialization (System Agent module specific)
18 - Pre-Memory System Agent initialization (System Agent module specific)
19 - Pre-memory PCH initialization is started
1A - Pre-memory PCH initialization (PCH module specific)
1B - Pre-memory PCH initialization (PCH module specific)
1C - Pre-memory PCH initialization (PCH module specific)
1D - OEM pre-memory initialization codes
1E - OEM pre-memory initialization codes
1F - OEM pre-memory initialization codes
20 - OEM pre-memory initialization codes
21 - OEM pre-memory initialization codes
22 - OEM pre-memory initialization codes
23 - OEM pre-memory initialization codes
24 - OEM pre-memory initialization codes
25 - OEM pre-memory initialization codes
26 - OEM pre-memory initialization codes
27 - OEM pre-memory initialization codes
28 - OEM pre-memory initialization codes
29 - OEM pre-memory initialization codes
2A - OEM pre-memory initialization codes
2B - Memory initialization. Serial Presence Detect (SPD) data reading
2C - Memory initialization. Memory presence detection
2D - Memory initialization. Programming memory timing information
2E - Memory initialization. Confi guring memory
2F - Memory initialization (other)
30 - Reserved for ASL (see ASL Status Codes section below)
31 - Memory Installed
32 - CPU post-memory initialization is started
33 - CPU post-memory initialization. Cache initialization
34 - CPU post-memory initialization. Application Processor(s) (AP) initialization
35 - CPU post-memory initialization. Boot Strap Processor (BSP) selection
36 - CPU post-memory initialization. System Management Mode (SMM) initialization
37 - Post-Memory System Agent initialization is started
38 - Post-Memory System Agent initialization (System Agent module specific)
39 - Post-Memory System Agent initialization (System Agent module specific)
3A - Post-Memory System Agent initialization (System Agent module specific)
3B - Post-Memory PCH initialization is started
3C - Post-Memory PCH initialization (PCH module specific)
3D - Post-Memory PCH initialization (PCH module specific)
3E - Post-Memory PCH initialization (PCH module specific)
3F - OEM post memory initialization codes
40 - OEM post memory initialization codes
41 - OEM post memory initialization codes
42 - OEM post memory initialization codes
43 - OEM post memory initialization codes
44 - OEM post memory initialization codes
45 - OEM post memory initialization codes
46 - OEM post memory initialization codes
47 - OEM post memory initialization codes
48 - OEM post memory initialization codes
49 - OEM post memory initialization codes
4A - OEM post memory initialization codes
4B - OEM post memory initialization codes
4C - OEM post memory initialization codes
4D - OEM post memory initialization codes
4E - OEM post memory initialization codes
4F - DXE IPL is started
PEI Error Codes
50 - Memory initialization error. Invalid memory type or incompatible memory speed
51 - Memory initialization error. SPD reading has failed
52 - Memory initialization error. Invalid memory size or memory modules do not match
53 - Memory initialization error. No usable memory detected
54 - Unspecifi ed memory initialization error
55 - Memory not installed
56 - Invalid CPU type or Speed
57 - CPU mismatch
58 - CPU self test failed or possible CPU cache error
59 - CPU micro-code is not found or micro-code update is failed
5A - Internal CPU error
5B - reset PPI is not available
5C - Reserved for future AMI error codes
5D - Reserved for future AMI error codes
5E - Reserved for future AMI error codes
5F - Reserved for future AMI error codes
