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funker
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Joined: 07 Nov 2013
Posts: 18

PostPosted: Sun Dec 13, 2015 8:13 pm    Post subject: Gentoo EFI Stub Kernel Reply with quote

Hello,

I've got problems with booting my efi-stub-kernel. My harddisk is partitionid with the following scheme using cgdisk:

Code:
/dev/sda1  --> 512MB, vfat -F 32, ESP (Efi System Partition)
/dev/sda2  --> 64gb, ext4, Linux Root Partition
/dev/sda3  --> remaining space, ext4, Linux Home Partition


/etc/fstab is configured correctly according to Sakaki's EFI-Gentoo-Guide and worked well on other systems like my Acer 1810T (altough it's booting without UEFI using grub2)

the kernel-image lies on /dev/sda1 within the following folder: /efi/boot/gentoo.efi; nothing else is present on this drive - I've copied /usr/src/linux/arch/x86_64/boot/bzImage to /EFI/efi/boot/gentoo.efi

The kernel was configured using menuconfig and everything necessary for efi-stub-booting has been enabled according to gentoo.org's efi-stub-wiki-article.
The kernel's internal cmd line: root=/dev/sda2 (which is my root partition as shown above). Afterwards I've created my boot-entry:

Code:
efibootmgr -c -d /dev/sda -p 1 -L "Gentoo Linux" -l '\efi\boot\gentoo.efi' -u root=/dev/sda2


After I choose "Gentoo Linux" from my boot-menu, my screen turns off almost instantly displaying a message like "No cable connected!" and my box seems like frozen - only a hard-reset let's me turn it off or let it reboot.

Can anyone help me to find a solution?

Thanks a lot :)
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transsib
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Joined: 26 Jul 2003
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PostPosted: Mon Dec 14, 2015 6:04 am    Post subject: Reply with quote

I don't know much about stub.
Shot in the dark:
what video card?
have you modprobe efivars before chroot/before the mount commands preparing chroot ( if this is necessary for stub ) ?

Have you solved your issue already? If yes what was the problem?
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funker
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Joined: 07 Nov 2013
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PostPosted: Mon Dec 14, 2015 4:50 pm    Post subject: Reply with quote

Thanks for your answer!

I've got a Godavari APU (AMD 7870K), so I believe "amdgpu" would be the right choice within the category of graphics devices in my kernel config. I've never heard of "modprobe efivars" before, I thought it would be sufficient to boot the install-iso in uefi mode (gpt-partitioned stick with system rescue cd). "efivars -l" shows quite a large amount of output. I'll look into the whole issue a little bit more, but up to now I'm out of options, so I wouldn't mind any other hints :)
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Perfect Gentleman
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PostPosted: Mon Dec 14, 2015 5:27 pm    Post subject: Reply with quote

is amdgpu in kernel or module ?
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chithanh
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Joined: 05 Aug 2006
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PostPosted: Mon Dec 14, 2015 7:31 pm    Post subject: Reply with quote

radeon is the correct driver for that Kaveri APU. amdgpu is by default only used for Carrizo and newer APUs.

If you have DRM_RADEON=y then you need to build the firmware into the kernel. If you skip this step, then your boot will hang for 60 seconds while the kernel tries to load the firmware.
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transsib
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Joined: 26 Jul 2003
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PostPosted: Mon Dec 14, 2015 7:43 pm    Post subject: Reply with quote

So you have a CPU with integrated graphics. Do you have an expansion video card too?
An expansion card needs a UEFI capable firmware.

Can you boot your new system at all?
I suppose not or am I wrong? If you can boot into your system
is folder /sys/firmware/efi/efivars/ populated?
Your system needs the efi variables.

When installing a new Gentoo system in efi on a gpt harddrive I have made the
experience that if you do not modprobe efivars before mounting dev and sys and
then chrooting your new system does not have the efi variables and cannot boot in efi mode later.
I have learned that the hard way. By modprobing efivars mount --rbind /sys /mnt/gentoo/sys
and mount --make-rslave /mnt/gentoo/sys transfer them into your new system and you´ve got them when you
chroot and install grub2 or whatever you do to make your Gentoo bootable.

I hope you find someone with knowledge about processor integrated video.
My CPU is a Xeon Haswell; it does not have on-board video. So I do not know whether it has to be a module
or not.

Better people on this forum: please correct me if I am wrong :)
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funker
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PostPosted: Mon Dec 14, 2015 9:19 pm    Post subject: Reply with quote

Building the kaveri-firmware into the kernel was the best hint so far, however, the kernel panics at boot (I believe due to a misconfiguration regarding SATA-Controllers - couldn't find/mount/whatever my root partition, altough it's set to root=/dev/sda2 via kernel command line). Nevertheless I'm happy to see my first stub kernel "boot" - at least I can see something on my monitor ;)

EDIT: System is booting, I've appended the root's partition twice (with efibootmgr .... -u root=... and within the kernel's command line)

EDIT2: Hm, can't find out how to configure my usb keyboard... shall I enable USB_KBD=y?

EDIT3: CONFIG_HID_CHERRY=y solved this issue... nevermind :)
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