[coreboot] Lenovo Carbon X1

Sun Dec 13 12:25:42 CET 2015

Hi,

I want to start a port on the Lenovo Carbon X1. I'm a BIOS newbie and don't 
know much about chipsets, so I'll need your support here.
But I've enough C programming experience to get the job done with your 
help (I hope).

At the moment I'm collecting information about the hardware:

The mainboard has two flash chips:
EN25QH64: 8MB Flash
MX25L3206E: 4MB Flash

I know already from IRC that "Intel Corporation 3rd Gen Core processor" 
means Ivy bridge. That's all for now.

Hopefully somebody can help me with identifying all necessary chipset info 
from the lspci and dmidecode output below.

Then I've a lot of questions:

1.) What is the minimum configuration to get started and a linux kernel 
booted?
northbridge, southbridge, RAM init? what else?
Because the kernel can be a payload in the flash even SATA controller is 
not necessary, right?
Advanced stuff as network boot is not necessary.

2.) From my basic understanding I believe as soon as the kernel gets 
executed everything else gets initialized by the kernel and the BIOS is not 
needed anymore. Is that right?

3.) For diagnostics I think VGA output is necessary.
This board has no UART, only USB, and this would require initializing USB 
controller and communicating using a usb/serial converter.
What do you think is the easier way for debug output?

I've already read this article here: http://www.coreboot.org/VGA_support[1] 
And it seems like extracting the VGA ROM via the kernel works here:

lspci -tv:
-[0000:00]-+-00.0  Intel Corporation 3rd Gen Core processor DRAM 
Controller
           +-02.0  Intel Corporation 3rd Gen Core processor Graphics 
...

ls -l /sys/devices/pci0000:00/0000:00:02.0/rom
-rw------- 1 root root 131072 Dec 13 12:16 
/sys/devices/pci0000:00/0000:00:02.0/rom

echo 1 > /sys/devices/pci0000:00/0000:00:02.0/rom
cp /sys/devices/pci0000:00/0000:00:02.0/rom vgabios.bin
hexdump -C vgabios.bin > vgabios.bin.hex

Here are the 1st 10 lines of the vgabios hexdump:
00000000  55 aa 80 e9 78 ea 30 30  30 30 30 30 30 30 30 30  |
U...x.0000000000|
00000010  30 30 40 25 e9 59 24 97  40 00 b0 0a 30 30 49 42  |
00@%.Y$. at ...00IB|
00000020  4d 20 56 47 41 20 43 6f  6d 70 61 74 69 62 6c 65  |M VGA 
Compatible|
00000030  20 42 49 4f 53 2e 20 03  6e 00 7e 00 8c 00 8b c0  | BIOS. 
.n.~.....|
00000040  50 43 49 52 86 80 06 01  1c 00 1c 00 03 00 00 03  |
PCIR............|
00000050  80 00 00 00 00 80 80 00  00 00 00 00 06 01 16 01  |................|
00000060  26 01 56 01 66 01 76 01  86 01 00 00 6e 03 00 c0  |
&.V.f.v.....n...|
00000070  00 00 00 00 00 00 00 00  00 00 00 00 88 00 00 c0  |................|
00000080  00 00 00 00 00 00 00 00  1a 00 37 03 00 c0 00 00  
|..........7.....|
00000090  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|

looks promising ;-)

More info about the HW comes here:

lspci output:
00:00.0 Host bridge: Intel Corporation 3rd Gen Core processor DRAM 
Controller (rev 09)
00:02.0 VGA compatible controller: Intel Corporation 3rd Gen Core 
processor Graphics Controller (rev 09)
00:14.0 USB controller: Intel Corporation 7 Series/C210 Series Chipset 
Family USB xHCI Host Controller (rev 04)
00:16.0 Communication controller: Intel Corporation 7 Series/C210 Series 
Chipset Family MEI Controller #1 (rev 04)
00:16.3 Serial controller: Intel Corporation 7 Series/C210 Series Chipset 
Family KT Controller (rev 04)
00:1a.0 USB controller: Intel Corporation 7 Series/C210 Series Chipset 
Family USB Enhanced Host Controller #2 (rev 04)
00:1b.0 Audio device: Intel Corporation 7 Series/C210 Series Chipset Family 
High Definition Audio Controller (rev 04)
00:1c.0 PCI bridge: Intel Corporation 7 Series/C210 Series Chipset Family 
PCI Express Root Port 1 (rev c4)
00:1c.1 PCI bridge: Intel Corporation 7 Series/C210 Series Chipset Family 
PCI Express Root Port 2 (rev c4)
00:1d.0 USB controller: Intel Corporation 7 Series/C210 Series Chipset 
Family USB Enhanced Host Controller #1 (rev 04)
00:1f.0 ISA bridge: Intel Corporation QS77 Express Chipset LPC Controller 
(rev 04)
00:1f.2 SATA controller: Intel Corporation 7 Series Chipset Family 6-port 
SATA Controller [AHCI mode] (rev 04)
00:1f.3 SMBus: Intel Corporation 7 Series/C210 Series Chipset Family SMBus 
Controller (rev 04)
02:00.0 System peripheral: Ricoh Co Ltd PCIe SDXC/MMC Host Controller 
(rev 07)
03:00.0 Network controller: Intel Corporation Centrino Advanced-N 6205 
[Taylor Peak] (rev 96)

lsusb output:
Bus 002 Device 003: ID 0bdb:1926 Ericsson Business Mobile Networks BV 
Bus 002 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching 
Hub
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 005: ID 04f2:b315 Chicony Electronics Co., Ltd 
Bus 001 Device 004: ID 0a5c:21e6 Broadcom Corp. BCM20702 Bluetooth 
4.0 [ThinkPad]
Bus 001 Device 003: ID 147e:2020 Upek TouchChip Fingerprint 
Coprocessor (WBF advanced mode)
Bus 001 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching 
Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

dmidecode output:
# dmidecode 2.12
SMBIOS 2.7 present.
71 structures occupying 2762 bytes.
Table at 0xDAE9D000.

Handle 0x0000, DMI type 134, 16 bytes
OEM-specific Type
	Header and Data:
		86 10 00 00 00 53 54 4D 20 01 01 00 00 03 01 
02
	Strings:
		TPM INFO
		System Reserved

Handle 0x0001, DMI type 4, 42 bytes
Processor Information
	Socket Designation: CPU Socket - U3E1
	Type: Central Processor
	Family: Core i7
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