Bug #310
closed
Coreboot 4.14 fails on a Lenvovo T440p
Added by David Hoelscher over 3 years ago.
Updated about 2 years ago.
Affected hardware:
ThinkPad T440p
Affected OS:
All (coreboot bug)
Description
Hi all,
coreboot 4.14 dies on early boot. The T440p ended with led blinking and beep sound.
This was my first try - so i think it was maybe a problem with mrc.bin or vga.rom. But if I skip back to version 4.13, everything works fine (4.13 working config is appended). I don't know how to get debug information on this early stage of boot. Does anyone has a hint? A Raspberry Pi as an external flasher is available.
Further - is it possible to flash only the 4 MB BIOS chip? This IC is very easy accessible. I am afraid to disassemble the complete backplate to access the other 8MB chip again. Initially I flashed the complete Rom without ME on both chips.
Files
I flashed each T440p-related commit made after the 4.13 release until I found the one that no longer boots. This appears to be the breaking change:
https://review.coreboot.org/plugins/gitiles/coreboot/+/ae999503f62ef8a3b9b2756a2810d29c383a009e
I tried reverting the changes made in this commit (PEG_CAP,PEG_DCAP,etc) and was then able to build from master/4.14 and get a bootable, working 4.14 ROM for the T440p. FWIW my T440p doesn't have a dGPU.
Side note: Flashing only the 4MB chip seems to work (for me, anyway) to get the system booting again.
A coreboot log would tell what exactly is going on. You can use flashconsole (CONSOLE_SPI_FLASH Kconfig option) to retrieve one. I think I know what's going on, though: the straps on the mainboard enable PEG x8/x8 bifurcation, which means there's a PCI device at 00:01.0 (Bus:Dev.Func) where the dGPU would be connected to, and another unused PCI device at 00:01.1 which is not present in the devicetree. The config_of() function call added in that commit makes coreboot die when it runs for PCI device 00:01.1 because the device node isn't linked to any chip.
- Status changed from New to Response Needed
- Assignee set to Angel Pons
- % Done changed from 0 to 100
Angel Pons wrote:
A coreboot log would tell what exactly is going on. You can use flashconsole (CONSOLE_SPI_FLASH Kconfig option) to retrieve one. I think I know what's going on, though: the straps on the mainboard enable PEG x8/x8 bifurcation, which means there's a PCI device at 00:01.0 (Bus:Dev.Func) where the dGPU would be connected to, and another unused PCI device at 00:01.1 which is not present in the devicetree. The config_of() function call added in that commit makes coreboot die when it runs for PCI device 00:01.1 because the device node isn't linked to any chip.
I can confirm adding device pci 01.1 off end # Unused PCIe Bridge to devicetree.cb resolves the issue for me. I can now build (and boot!) master. Thanks so much Angel!
Yes, I also can confirm that your patches resolve this issue. Thank you very much!
I can confirm this issue and I can confirm as well that current master works (opposed to 4.14).
- Status changed from Response Needed to Resolved
- Affected hardware set to ThinkPad T440p
- Affected OS set to All (coreboot bug)
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