Re: [Xen-devel] Re: Continuing problems booting

[Gerd Hoffmann <kraxel@xxxxxxxxxx>]

Jeremy Fitzhardinge wrote:
> Gerd Hoffmann wrote:
>>> I can watch the cursor moving, just no characters appear on the screen.
>>>  Maybe some I/O port access issue?  So the color palette is foobar and
>>> it prints black on black?
>>>     
>>
>> Hmm, funny thing is, earlyprintk=vga _does_ print something. Looks
>> incomplete though (scrolls by quickly) and of course the early console
>> stops anyway as soon as the vga console takes over.
> 
> Ah, yes. I'd noticed that and forgotten about it.  Well.  What the hell
> does that mean?

Memory mapping issue.  Seems to break during init_memory_mapping().

I can slowly print lines on /dev/tty0 using a shell loop with a sleep in
there.  Doesn't print anything on the screen.  I can see the stuff
printed by earlyvga scroll through the screen though.  Thus vga register
access (for panning) works just fine.  Accessing the memory probably
ends up somewhere else due to the mappings not being setup correctly.

Last line of earlyvga output is this:
  init_memory_mapping: 0000000000000000-000000001d001000

Note that init_memory_mapping () has this close to the end if the function:

   #ifdef CONFIG_X86_32
        early_ioremap_page_table_range_init();
        load_cr3(swapper_pg_dir);
   #endif

i.e. early iomap setup is different in 32bit and 64bit.  Which would
also explain why vgacon works just fine in 64bit mode.

cheers,
  Gerd



_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel