Xen users - Dec 2013 - Xen black screens while booting in Arch Linux with UEFI GRUB

I posted this on Arch Linux Forums but didn''t received any help, and
due to the fact that I don''t know if its an OS-related or Xen-related
issue, I prefer to ask in both places to see if I can get an
answer.https://bbs.archlinux.org/viewtopic.php?id=174184
Basically, the issue I have goes like this: After installing Arch Linux in UEFI
mode, I install Xen on top of it following Arch Linux wiki instructions for Xen.
GRUB allows me to choose to load Xen Arch, it starts to boot but suddently black
screens right after saying how many CPUs it has detected. If on xen.conf I limit
the amount of RAM for Dom0 then generate a grub.cfg file with the changes, it
black screens after the Scrubbing RAM step, which is an extra step right after
the CPU detection.
Some days ago I managed to get Xen working relatively well on my current machine
(I didn''t manage to do VGA passthrough - that will come at a later
stage. But could install WXP on a LVM partition and the GPLPV Drivers), however,
at that time I partitioned using MBR and my Boot Loader was Syslinux. As most
examples on Internet for the Xen Boot Loader configuration are for GRUB, not
Syslinux, I decided to reinstall from scratch and do a proper installation in
UEFI mode and GPT partitioned. After several fresh and fully documented
installations, I didn''t manage to get Xen working since then.

Due to the fact that I''m still new on Linux (Less than two weeks using
Arch Linux) and still didn''t learned how to properly use debugging
tools, logs and such, I can''t really put a log of actual issue unless
someone explains me how to do so. So for a first Post, until further
instructions about what I can do to provide more info, the most data that I can
give you is just a step-by-step of what I do after a fresh install of Arch Linux
and Xen that causes the issue, to see if anyone can notice if I missed something
which isn''t on the wikis and not easy to google without the proper
keywords.



HARDWAREProcessor: Xeon E3-1245 V3 (Haswell)Motherboard: Supermicro X10SAT
(Chipset C226)RAM: 32 GB (4 * 8 GB) AMD Performance Edition RP1866
Unbuffered/Non-ECCHD: Seagate Desktop HDD.15 4 TBVideo Card: Both integrated
Intel HD Graphics 4600 and a Radeon 5770 intended for GPU passthrough on Xen,
will add a second 5770 laterPower Supply: Seasonic S12II-520Monitors: Samsung
SyncMaster 2370H (DVI) and 932N+ (VGA), both currently plugged on the Intel HD
Graphics 4600
Any option that the BIOS allows me to choose between Legacy-only or UEFI-only,
is configured as UEFI-only. This applies to PCI Express Slots Option ROMs.Video
Card order is IGP first, so the Radeon shouldn''t have video output
unless after an OS is loaded.All common-sense options (VT-x, VT-d, Hyper
Threading, etc) I recognized are enabled.Additional controllers like the ASMedia
for SATA-3 Ports or Intel NIC booting ROM are disabled.


SOFTWAREarchlinux-2013.12.01-dual.iso (Latest)I wrote the ISO to a Pendrive with
dd following these instructions here to make it boot with UEFI
modehttps://wiki.archlinux.org/index.php/USB_Flash_Installation_Media#Using_dd_.28Recommended_method.29
xen package from Arch User Repository (Should be 4.3.1-2)Some misc packages.

I do a fresh installation of Arch Linux following their wiki
instructionshttps://wiki.archlinux.org/index.php/Beginners%27_Guide
efivar -l gives output after booting from the UEFI Pendrive, confirming
I''m running on UEFI mode.Partitioned the HD with gdisk. Reelevant
partitions are a 512 MiB EFI System Partition, a 9.5 GiB for Dom0 Arch Linux
with Xen, and some bigger unformatted partitions for LVM.Formatted only the ESP
and next-to-be Dom0 partitions with FAT32 and EXT4 respectivel, using mkfs.fat
and mkfs.ext4Mounted /dev/sda2 to /mnt and /dev/sda1 to /mnt/boot.Installed Arch
Linux to /mnt via pacstrap, with both base and base-devel packages.Used genfstab
to generate /etc/fstab. Contents are the two mounted partitions.Chrotted into
/mnt with /bin/bash parameters.Some basic configuration: /etc/vconsole.conf,
uncommenting some lines on locale.gen, using locale-gen then using export on
one. Symlinked appropiate timezone.Enabled DHCP service with systemctl to have
Internet ready on next boot (Wired, comes via NIC).Used pacman to install grub,
efibootmgr and dosfstools.Installed GRUB with grub-install --target=x86_64-efi
--efi-directory=/boot --bootloader-id=arch_grub --recheckModified
/etc/default/grub to add GRUB_DISABLE_SUBMENU=y line to fix some errors that
were popping out with grub-mkconfig and latest Arch Linux ISO.Generated grub.cfg
with grub-mkconfig -o /boot/grub/grub.cfgExited, umounted both partitions,
rebooted.
On the Boot tab, BIOS sees UEFI:arch_grub. It boots fine.After first boot from
the Arch Linux installation, I resume preparing for Xen:
Modified /etc/pacman.conf to uncomment the [multilib] and its include line, then
did pacman -SyyuManually installed package-query and yaourt packages (curl -O,
tar, makepkg) from the AUR repository. No issues to install eitherUsed yaourt to
download xen. It downloads xen and its dependancies with no issues, compiles and
install them
Then, I follow the instruccions here:https://wiki.archlinux.org/index.php/XenUse
grub-mkconfig to add Xen to the GRUB menu options. It recognizes Xen image and
completes sucessfully.Create the Network Bridge xenbr0 with netctl. It works.Use
systemctl to enable xenstored.service, xenconsoled.service and
xendomains.serviceReboot
Now I have the Arch Xen option in the GRUB menu. Choosing it loads the images,
loads the RAMDisk, then changes my Monitor to 640x480 (Or it seems like), and
starts to boot until it reachs the CPU detected step and black screens. One of
the things I managed to test was editing /etc/xen/grub.cfg, by decommenting the
XEN_HYPERVISOR_CMDLINE line with xsave=1 and adding dom0_mem=2048M. After
remaking grub.cfg with grub-mkconfig, it does an extra step after CPU detection
where it says "Scrubbing RAM", after it finishes it black screens.
Several tries, fresh installations fully documented (A bit more detailed than
above), I didn''t manage to make it work.The standalone Arch stills work
fine. Booting with it, I checked the xenconsoled service status and it complains
that it failed to start because ConditionPathExist=/proc/xen was not met. The
only other place where I saw /proc/xen was on a line that is recommended to be
added to fstab for xenfs, which I also tried. After rebooting, Arch Linux throws
me to maintenance mode for as long as that line is there, and Arch Xen keeps
black screening on the same step. I suppose it could be because /proc/xen
depends on booting with the Xen image, which is what I wasn''t able to
do, so that error is consequence of that.Additionally, I also did a manual
install of Syslinux for UEFI. I could get it working with Arch Linux, but as
soon as I choose the Xen option, it instantly crashes. I''m using the
parameters from Arch Linux wiki Xen
article:https://wiki.archlinux.org/index.php/xen#Modification_of_the_bootloader


After googling a lot, I got stuck in this point and didn''t really
manage to go beyond it. I wasn''t able to use Xen with UEFI. However,
I''m not sure if Xen can or can''t be used, at least for the 4.2
version I found this:http://www.youtube.com/watch?v=-XFyPo7PacM...but not sure
if it applies to 4.3+.

The only ideas I have:
1 - Parameters that I can try for xen menu option in grub.cfg2 - I heared that
Xen can be compiled as a .efi file to be used with UEFI, but don''t know
if its mandatory or not. I would need a detailed guide about how to do so.
I could post more data or logs if you tell me how to get them.

Thanks for reading.

 
 		 	   		  

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On Sat, 2013-12-14 at 03:49 -0300, Zir Blazer wrote:
> Basically, the issue I have goes like this: After installing Arch
> Linux in UEFI mode, I install Xen on top of it following Arch Linux
> wiki instructions for Xen. GRUB allows me to choose to load Xen Arch,
I don''t know if this is related but AFAIK Xen does not currently
support
being launched under UEFI via a bootloader.

Instead xen.efi is a UEFI application which can be launched from the EFI
shell directly (i.e. instead of grub.efi).

http://xenbits.xen.org/docs/4.3-testing/misc/efi.html has some details
of the config file used here.

People are working on launching Xen via bootloaders under UEFI but I
don''t think it is complete/available yet in any released (or unreleased
ror that matter) version of Xen.

(BTW, you didn''t say what version of Xen you are using, not too
relevant
this time, but please remember next time).

Ian.

On Wed, 2013-12-18 at 04:03 -0300, Zir Blazer wrote:
> GRUB UEFI-GPT: [...]
> Syslinux UEFI-GPT: [...]
> Gummiboot UEFI-GPT + EFI file: [...]
> Due to the fact that I tested three different Boot Loaders 
As I said in my original reply xen.efi is supposed to be booted directly
from the EFI shell, not via a bootloader.

Whether or not that is your problem I don''t know, but that is what I
believe is supposed to work, whereas all these others are unknowns, so
please try that. (this is because Xen needs to be called EFI Boot
Services still available and bootloaders tend to call ExitBootServices
before calling the kernel)

If it still doesn''t work then I think you should report to the -devel
list as a potential bug. According to the MAINTAINERS the relevant
maintainer to CC is Jan Beulich <jbeulich@suse.com>.
> I *STILL* didn''t managed to get my Radeon 5770 passthroughed
properly
> (I think I should leave this for another mail with a proper topic,
> but...)
Yes, please, VGA passthrough is an entirely different can of worms.
> Its 4.3.1-2. I actually mentioned it in previous mail, but you
> probabily missed it due to my amazing wall of text :D
Yes I did, sorry.

Ian.