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1# ASUS P2B-LS
2
3This page describes how to run coreboot on the ASUS P2B-LS mainboard.
4
5## Variants
6
7- P2B-LS
8- P2B-L (Same circuit board with SCSI components omitted)
9- P2B-S (Same circuit board with ethernet components omitted)
10
11## Flashing coreboot
12
13```{eval-rst}
14+---------------------+---------------------------+
15| Type                | Value                     |
16+=====================+===========================+
17| Model               | SST 39SF020A (or similar) |
18+---------------------+---------------------------+
19| Protocol            | Parallel                  |
20+---------------------+---------------------------+
21| Size                | 256 KiB                   |
22+---------------------+---------------------------+
23| Package             | DIP-32                    |
24+---------------------+---------------------------+
25| Socketed            | yes                       |
26+---------------------+---------------------------+
27| Write protection    | no                        |
28+---------------------+---------------------------+
29| Dual BIOS feature   | no                        |
30+---------------------+---------------------------+
31| Internal flashing   | yes                       |
32+---------------------+---------------------------+
33```
34
35[flashrom] works out of the box since 0.9.2.
36Because of deficiency in vendor firmware, user needs to override the laptop
37warning as prompted. Once coreboot is in place there will be no further issue.
38
39### CPU microcode considerations
40
41By default, this board includes microcode updates for 5 families of Intel CPUs
42because of the wide variety of CPUs the board supports, directly or with an
43adapter. These take up a third of the total flash space leaving only 20kB free
44in the final cbfs image. It may be necessary to build a custom microcode update
45file by manually concatenating files in 3rdparty/intel-microcode/intel-ucode
46for only CPU models that the board will actually be run with.
47
48## Working
49
50- Slot 1 and Socket 370 CPUs and their L1/L2 caches
51- PS/2 keyboard with SeaBIOS (See [Known issues])
52- IDE hard drives
53- Ethernet (-LS, -L; Intel 82558)
54- SCSI (-LS, -S; Adaptec AIC7890)
55- USB
56- ISA add-on cards
57- PCI add-on cards
58- AGP graphics card
59- Floppy
60- Serial ports 1 and 2
61- Reboot
62- Soft off
63
64## Known issues
65
66- PS/2 keyboard may not be usable until Linux has completely booted.
67  With SeaBIOS as payload, setting keyboard initialization timeout to
68  500ms may fix the issue.
69
70- i440BX does not support 256Mbit RAM modules. If installed, coreboot
71  will attempt to initialize them at half their capacity anyway
72  whereas vendor firmware will not boot at all.
73
74- ECC memory can be used, but ECC support is still pending.
75
76- Termination is enabled for all SCSI ports (if equipped). Support to
77  disable termination is pending. Note that the SCSI-68 port is
78  always terminated, even with vendor firmware.
79
80## Untested
81
82- Parallel port
83- EDO memory
84- Infrared
85- PC speaker
86
87## Not working
88
89- S3 suspend to RAM
90
91## Technology
92
93```{eval-rst}
94+------------------+--------------------------------------------------+
95| Northbridge      | Intel I440BX                                     |
96+------------------+--------------------------------------------------+
97| Southbridge      | i82371eb                                         |
98+------------------+--------------------------------------------------+
99| CPU              | P6 family for Slot 1 and Socket 370              |
100|                  | (all models from model_63x to model_6bx)         |
101+------------------+--------------------------------------------------+
102| Super I/O        | winbond/w83977tf                                 |
103+------------------+--------------------------------------------------+
104```
105
106## Extra resources
107
108[flashrom]: https://flashrom.org/Flashrom
109