blank screen after kernel upgrade from 5.4.10 to 5.5.0-1

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Re: blank screen after kernel upgrade from 5.4.10 to 5.5.0-1

Postby JohnM » Tue Apr 28, 2020 5:49 pm

One thing I'd really like to know for when this happens again with a future update is how to recover without wiping the eMMC. I have Arch installed on /dev/mmcblk0p1 (kernel) and /dev/mmcblk0p2 (root) and my bootloader is still owned by Google, just like the OP. However, I'm unable to boot from a USB stick. CTL-U at the scary power-on screen just makes two loud beeps but is otherwise ignored so when I updated to the bad kernel my only option was to use a Chrome OS recovery medium (actually, an SD card), then from Chrome get a root terminal and enable booting from external storage. Once done I was able to boot from that same USB stick, then re-install to the eMMC. Obviously, I'd prefer to repair the problem rather than start from scratch. Once I've booted Arch using CTL-D I seem to lose the ability to use CTL-U.
JohnM
 
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Re: blank screen after kernel upgrade from 5.4.10 to 5.5.0-1

Postby vacant » Tue Apr 28, 2020 7:28 pm

I recently decided to delve into this and now have a "magic" USB flash drive that boots and can rescue both my Samsung ARM Chromebook and my Acer Intel laptop Arch systems.

If CTRL-U beeps at you when the flash drive is in the USB 2 port then perhaps your chromebook hasn't got

Code: Select all
crossystem dev_boot_usb=1 dev_boot_signed_only=0


or the flash drive kernel partition hasn't got the custom ChromeOS boot flags (that gdisk doesn't know about but cgpt and x64-cgpt do -S, -T, -P)

Code: Select all
cgpt add -i 1 -t kernel -b 8192 -s 32768 -l Kernel -S 1 -T 5 -P 10 /dev/sda


Here's the layout according to gdisk (partition 3 is a grub boot partition, 5 is an encrypted full system backup of the chromebook if it is missing dev_boot_usb and a ChromeOS restore is the only way to go)

Code: Select all
Number  Start (sector)    End (sector)  Size       Code  Name
   1            2048           34815   16.0 MiB    7F00  ChromeOS kernel
   2           34816         4229119   2.0 GiB     8300  samsung rescue
   3         4229120         4231167   1024.0 KiB  EF02  BIOS boot partition
   4         4231168        12619775   4.0 GiB     8300  acer rescue
   5        12619776        30870043   8.7 GiB     8300  encrypted


Samsung Chromebook decides to boot from partition 1, Acer Laptop decides to boot from 3.

When it comes to rescue, I have good kernels stored on the flash drive, installed with arch-chroot for intel and "pacman -U -r /mnt" for the chromebook.
vacant
 
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Re: blank screen after kernel upgrade from 5.4.10 to 5.5.0-1

Postby pbgapski » Fri Jun 26, 2020 3:08 pm

JohnM wrote:One thing I'd really like to know for when this happens again with a future update is how to recover without wiping the eMMC. I have Arch installed on /dev/mmcblk0p1 (kernel) and /dev/mmcblk0p2 (root) and my bootloader is still owned by Google, just like the OP. However, I'm unable to boot from a USB stick. CTL-U at the scary power-on screen just makes two loud beeps but is otherwise ignored so when I updated to the bad kernel my only option was to use a Chrome OS recovery medium (actually, an SD card), then from Chrome get a root terminal and enable booting from external storage. Once done I was able to boot from that same USB stick, then re-install to the eMMC. Obviously, I'd prefer to repair the problem rather than start from scratch. Once I've booted Arch using CTL-D I seem to lose the ability to use CTL-U.


I have the same CTRL-U boot problem, and had the same fate with the kernel upgrade.

To double check, earlier this week I made a dd copy of emmc to a usb drive, and then recovered chromeos, enabled dev mode and usb boot, and disabled signed boot.

Then I booted with CTRL-U with the usb drive, and restored the emmc from the usb drive. At next reboot, CTRL-D took me to arch linux on the emmc.

However, on the boot screen, now the same usb drive gives me the double beep and does not boot.

Anyone understands this behavior or has some tips to share?
pbgapski
 
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Re: blank screen after kernel upgrade from 5.4.10 to 5.5.0-1

Postby ak404 » Tue Jul 14, 2020 12:05 pm

could it be the write protection you may have to double check and sometimes when putting it back together keep it pryed with something to make sure its not making contact. for crossytem / flashrom to work accordingly or something :D
ak404
 
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Re: blank screen after kernel upgrade from 5.4.10 to 5.5.0-1

Postby ak404 » Tue Jul 14, 2020 12:07 pm

i do find sharing this link is valuable too: ftp://ftp.arm.slackware.com/slackwarear ... NSTALL.txt

but reexaming the steps i can't spot it saving crossystem either
ak404
 
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