Re: [Xen-users] Garbled screen after RAM Scrub on boot

Re: [Xen-users] Garbled screen after RAM Scrub on boot

[George Dunlap]

Jan / Konrad,

Have you guys ever seen something like this before?  Any ideas how to proceed?

Thanks
 -George

On Tue, Feb 23, 2016 at 1:37 PM, Francis Greaves <francis@choughs.net> wrote:
> Dear All
> I am using Centos 7 with Xen 4.6 on a Dell Poweredge T430 with (from lspci)
> Matrox Electronics Systems Ltd. G200eR2 (rev 01) VGA
>
> When the machine boots, after the 'Scrubbing Free RAM' message, I get a
> screen filled with little white squares until the login prompt, so I cannot
> see what is happening as the machine boots. Also there is nothing on the
> screen when I reboot or shutdown.
>
> My /etc/default/grub is
>
> GRUB_DISTRIBUTOR="$(sed 's, release .*$,,g' /etc/system-release)"
> GRUB_DEFAULT=saved
> GRUB_DISABLE_SUBMENU=true
> GRUB_CMDLINE_LINUX="crashkernel=auto rhgb intremap=no_x2apic_optout"
> GRUB_CMDLINE_XEN_DEFAULT="dom0_mem=13312M,max:14336M dom0_max_vcpus=6
> dom0_vcpus_pin"
> GRUB_GFXMODE=1024x768
> GRUB_GFXPAYLOAD_LINUX=keep
> GRUB_CMDLINE_LINUX_XEN_REPLACE_DEFAULT="console=hvc0 earlyprintk=xen
> nomodeset"
>
> I have tried setting (for a 1024x768 resolution) vga=792 in the
> GRUB_CMDLINE_LINUX and commenting out GRUB_GFXMODE and
> GRUB_GFXPAYLOAD_LINUX, but this makes no difference.
> I have also tried with no settings for vga at all, and with and without
> 'rhgb'
> I have even tried bootscrub=false as suggested by the CentOS-virt mailing
> list, but that does not work either. They suggested I asked you folk.
>
> What am I doing wrong?
>
> Regards
> Francis
>
>
> _______________________________________________
> Xen-users mailing list
> Xen-users@lists.xen.org
> http://lists.xen.org/xen-users

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Re: [Xen-users] Garbled screen after RAM Scrub on boot

[Andrew Cooper]

On 07/03/16 14:33, George Dunlap wrote:
> Jan / Konrad,
>
> Have you guys ever seen something like this before?  Any ideas how to proceed?
>
> Thanks
>  -George

Sounds like the scrub is writing zeroes over the graphics framebuffer. 
This probably means that the firmware is using a region for the
framebuffer which isn't marked as reserved in the E820 region.

~Andrew

>
> On Tue, Feb 23, 2016 at 1:37 PM, Francis Greaves <francis@choughs.net> wrote:
>> Dear All
>> I am using Centos 7 with Xen 4.6 on a Dell Poweredge T430 with (from lspci)
>> Matrox Electronics Systems Ltd. G200eR2 (rev 01) VGA
>>
>> When the machine boots, after the 'Scrubbing Free RAM' message, I get a
>> screen filled with little white squares until the login prompt, so I cannot
>> see what is happening as the machine boots. Also there is nothing on the
>> screen when I reboot or shutdown.
>>
>> My /etc/default/grub is
>>
>> GRUB_DISTRIBUTOR="$(sed 's, release .*$,,g' /etc/system-release)"
>> GRUB_DEFAULT=saved
>> GRUB_DISABLE_SUBMENU=true
>> GRUB_CMDLINE_LINUX="crashkernel=auto rhgb intremap=no_x2apic_optout"
>> GRUB_CMDLINE_XEN_DEFAULT="dom0_mem=13312M,max:14336M dom0_max_vcpus=6
>> dom0_vcpus_pin"
>> GRUB_GFXMODE=1024x768
>> GRUB_GFXPAYLOAD_LINUX=keep
>> GRUB_CMDLINE_LINUX_XEN_REPLACE_DEFAULT="console=hvc0 earlyprintk=xen
>> nomodeset"
>>
>> I have tried setting (for a 1024x768 resolution) vga=792 in the
>> GRUB_CMDLINE_LINUX and commenting out GRUB_GFXMODE and
>> GRUB_GFXPAYLOAD_LINUX, but this makes no difference.
>> I have also tried with no settings for vga at all, and with and without
>> 'rhgb'
>> I have even tried bootscrub=false as suggested by the CentOS-virt mailing
>> list, but that does not work either. They suggested I asked you folk.
>>
>> What am I doing wrong?
>>
>> Regards
>> Francis
>>
>>
>> _______________________________________________
>> Xen-users mailing list
>> Xen-users@lists.xen.org
>> http://lists.xen.org/xen-users
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xen.org
> http://lists.xen.org/xen-devel


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Re: [Xen-users] Garbled screen after RAM Scrub on boot

[Jan Beulich]

>>> On 07.03.16 at 15:33, <George.Dunlap@eu.citrix.com> wrote:
> Have you guys ever seen something like this before?  Any ideas how to 
> proceed?

What Andrew said is one possibility. There could be others, depending
on when _exactly_ these odd little squares show up. However, as to
what Andrew suggests - afaict this ought to lead to a black screen,
since character zero is a blank one in all our fonts, not a little box
(which is usually used to represent unknown characters), and even
the character used in debug build (0xc2) isn't represented by a little
box in any of our fonts. I therefore suspect the problem to be
introduced by the Dom0 kernel, not the hypervisor.

Jan

> On Tue, Feb 23, 2016 at 1:37 PM, Francis Greaves <francis@choughs.net> wrote:
>> Dear All
>> I am using Centos 7 with Xen 4.6 on a Dell Poweredge T430 with (from lspci)
>> Matrox Electronics Systems Ltd. G200eR2 (rev 01) VGA
>>
>> When the machine boots, after the 'Scrubbing Free RAM' message, I get a
>> screen filled with little white squares until the login prompt, so I cannot
>> see what is happening as the machine boots. Also there is nothing on the
>> screen when I reboot or shutdown.
>>
>> My /etc/default/grub is
>>
>> GRUB_DISTRIBUTOR="$(sed 's, release .*$,,g' /etc/system-release)"
>> GRUB_DEFAULT=saved
>> GRUB_DISABLE_SUBMENU=true
>> GRUB_CMDLINE_LINUX="crashkernel=auto rhgb intremap=no_x2apic_optout"
>> GRUB_CMDLINE_XEN_DEFAULT="dom0_mem=13312M,max:14336M dom0_max_vcpus=6
>> dom0_vcpus_pin"
>> GRUB_GFXMODE=1024x768
>> GRUB_GFXPAYLOAD_LINUX=keep
>> GRUB_CMDLINE_LINUX_XEN_REPLACE_DEFAULT="console=hvc0 earlyprintk=xen
>> nomodeset"
>>
>> I have tried setting (for a 1024x768 resolution) vga=792 in the
>> GRUB_CMDLINE_LINUX and commenting out GRUB_GFXMODE and
>> GRUB_GFXPAYLOAD_LINUX, but this makes no difference.
>> I have also tried with no settings for vga at all, and with and without
>> 'rhgb'
>> I have even tried bootscrub=false as suggested by the CentOS-virt mailing
>> list, but that does not work either. They suggested I asked you folk.
>>
>> What am I doing wrong?
>>
>> Regards
>> Francis
>>
>>
>> _______________________________________________
>> Xen-users mailing list
>> Xen-users@lists.xen.org 
>> http://lists.xen.org/xen-users 




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