[Xen-devel] blank screen VGA or Serial while linux boot

[Daniele Palumbo <daniele@xxxxxxxxxxxx>]

Hi,

Sorry for bothering, I am following
https://wiki.xenproject.org/wiki/Xen_Serial_Console
and
http://www-archive.xenproject.org/files/xensummit_4/xensummit_linux_console_slides.pdf

And as written in
https://wiki.xenproject.org/wiki/XenParavirtOps
Here i am writing.

My goal is to have the same console output on VGA and internal serial port.

I am on gentoo, with Xen 4.6.4, custom kernel.
My kernel config is in attachment.

Test hardware is a Sun x4150, with ILOm.
Serial speed is set to 9600 bps, with console redirection (so all of the BIOS 
messages are shown).

See an example of my output in attachment (serial_out.txt), with the following 
settings:
GRUB_TERMINAL="console serial"
GRUB_SERIAL_COMMAND="serial --speed=9600 --unit=1 --word=8 --parity=no --stop=1"
GRUB_CMDLINE_XEN="loglvl=all guest_loglvl=all com1=9600,8n1 console=com1,vga"
GRUB_CMDLINE_LINUX="xencons=xvc console=xvc0 console=hvc0 console=tty1 
earlyprintk=xen nomodeset"
full grub.cfg in attachment.


As by the logs I am able to see the same terminal from BIOS to the XEN 
multiboot.
With xen multiboot i mean messages starting with
"(XEN) "
e.g.:
(XEN) Video information:Gentoo GNU/Linux (with Xen hypervisor)
(XEN)  VGA is text mode 80x25, font 8x16

I am not able to get the same message across serial _AND_ vga terminal upon 
boot,
AFTER the xen multiboot.

With earlyprintk=xen i see also linux messages starting with
"[    0.000000] "
e.g., last line seen is
[    0.000000] Memory: 925860K/2097148K available (5475K kernel code, 570K 
rwdata, 2344K rodata, 992K init, 1

After that, i can always see the login prompt in both serial and VGA output.


About grub config, the basic stuff in /etc/default/grub is:
"""
GRUB_TERMINAL="console serial"
GRUB_SERIAL_COMMAND="serial --speed=9600 --unit=1 --word=8 --parity=no --stop=1"
GRUB_CMDLINE_XEN="loglvl=all guest_loglvl=all com1=9600,8n1 console=com1,vga"
"""

nomodeset is not helping.

Seems like hvc0 contains only serial messages.
Seems also that setting 2 console in linux module would have exclusive access.
It is important to mention that i can always see grub and Xen logs in both 
serial and VGA device.
ttyS0 is not present at all in the dmesg.
# dmesg |grep tty
[    0.648440] 00:02: ttyS1 at I/O 0x2f8 (irq = 3, base_baud = 115200) is a 
16550A
#

Then i have tried out the following
# serial OK, no vga after XEN multiboot and earlyprintk
GRUB_CMDLINE_LINUX="console=hvc0 earlyprintk=xen"
# serial OK, no vga after XEN multiboot and earlyprintk
GRUB_CMDLINE_LINUX="console=hvc0 earlyprintk=xen nomodeset"
# serial OK, no vga after XEN multiboot and earlyprintk
GRUB_CMDLINE_LINUX="console=hvc0 earlyprintk=xen nomodeset vga=791"


# VGA OK, no serial after XEN multiboot  and earlyprintk
GRUB_CMDLINE_LINUX="console=hvc0 console=tty1 earlyprintk=xen"


# VGA OK, no serial after XEN multiboot  and earlyprintk
GRUB_CMDLINE_LINUX="console=xvc xencons=xvc console=hvc0 console=tty0 nomodeset 
earlyprintk=xen"

# VGA OK, no serial after XEN multiboot  and earlyprintk
GRUB_CMDLINE_LINUX="xencons=xvc console=xvc0 console=hvc0 console=tty1 
earlyprintk=xen nomodeset"

Really willing to understand how to get the proper output on both serial and 
VGA.

Thank you very much,
Daniele

Attachment: config-4.4.26-xen-Dom0-44-r2
Description: Binary data

Attachment: serial_out.txt
Description: Text document

Attachment: grub.cfg
Description: Binary data

Attachment: lspcivvv.txt
Description: Text document

Attachment: dmidecode.txt
Description: Text document

Attachment: signature.asc
Description: Message signed with OpenPGP using GPGMail

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