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Re: [Xen-devel] console: introduce console=none option

>>> On 26.01.12 at 15:58, Andrew Cooper <andrew.cooper3@xxxxxxxxxx> wrote:
> On 26/01/12 14:41, Jan Beulich wrote:
>>>>> On 26.01.12 at 13:19, Andrew Cooper <andrew.cooper3@xxxxxxxxxx> wrote:
>>> XenServer by default boots without a serial console (buggy hardware
>>> reasons) and dom0 displays a splash screen.  Unfortunately, having Xen
>>> writing to the vga text area looks ugly whilst dom0 is trying to set up
>>> non-text mode and display  the splash screen.
>>> We have been using "console=" to prevent this behavior for a while, but
>>> presented herewith is a patch to fix the problem correctly.
>> While I don't mind the patch, I'm completely confused by the description:
>> Where is it that Xen writes to VGA text area after control was passed to
>> Dom0?
>> Jan
> I have not debugged it that much as I was looking for a clean solution
> to our current hack of "console=" (and I have some rather more serious
> deadlock bugs to debug), but it all Xen printk's are going into the VGA
> text area, even after dom0 has started.  It is possible that Xen is
> still writing into the text area after dom0 has switched VGA mode, but I
> have no proof of this one way or the other.

Just take a look at vga_endboot() - the output routine gets pointed to
vga_noop_puts() unless vgacon_keep. Beyond that point nothing
can possibly get printed to the VGA text screen, or if it does, then I'd
suspect there's some other change in XenServer that makes it so.


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