Re: [Qemu-devel] Re: EFI console stopped working in Qemu 0.14.0

[vagran <vagran.ast@gmail.com>]

I am using TianoCore EFI by Tristan Gingold which is published
on http://wiki.qemu.org/download/efi-bios.tar.bz2. If you would try
to load it on Qemu 0.14.0 (built either for i386 or x86_64) you will
see nothing on VGA display or serial console. But it still will be
able to load OS after timeout if you have proper disk image.
> It seems your EFI BIOS doesn't enable memor, io or master bits
> in command register.
>   
>
> or disableintx.
>   
I have checked your guess and figured out that it works only
if both memory and io bits are not cleared. So the following
patch also works:
diff --git a/hw/pci.c b/hw/pci.c
index 8b76cea..bcf9b16 100644
--- a/hw/pci.c
+++ b/hw/pci.c
@@ -163,8 +163,9 @@ void pci_device_reset(PCIDevice *dev)
     pci_device_deassert_intx(dev);
     /* Clear all writeable bits */
     pci_word_test_and_clear_mask(dev->config + PCI_COMMAND,
-                                 pci_get_word(dev->wmask + PCI_COMMAND) |
-                                 pci_get_word(dev->w1cmask + PCI_COMMAND));
+                                 (pci_get_word(dev->wmask + PCI_COMMAND) |
+                                 pci_get_word(dev->w1cmask + 
PCI_COMMAND)) &
+                                 ~(PCI_COMMAND_IO | PCI_COMMAND_MEMORY));
     pci_word_test_and_clear_mask(dev->config + PCI_STATUS,
                                  pci_get_word(dev->wmask + PCI_STATUS) |
                                  pci_get_word(dev->w1cmask + PCI_STATUS));

So probably the problem is in EFI BIOS. But I was not able to find
its source code. Anyone knows how is it built?

Best regards,
Artyom.


Isaku Yamahata wrote:
> On Thu, Mar 03, 2011 at 12:03:53PM +0900, Isaku Yamahata wrote:
>   
>> Hi. Thank you for reporting.
>> Can you elaborate on the changeset that you pointed out and
>> your work around?
>>
>> Regarding to the changeset, it had the issue, but I suppose
>> 80376c3fc2c38fdd45354e4b0eb45031f35587ed fixed it.
>> Do you found any other issue?
>>
>> Regarding to your workaround, what was the problem?
>> What EFI BIOS are you using? Tiano-core derivatives that
>> Tristan Gingold worked on? Or other one?
>> It seems your EFI BIOS doesn't enable memor, io or master bits
>> in command register.
>>     
>
> or disableintx.
>
>   
>> If so, the issue is in the bios, not qemu.
>>
>> thanks,
>>
>> On Wed, Mar 02, 2011 at 11:27:31PM +0200, vagran wrote:
>>     
>>> vagran wrote:
>>>       
>>>> Hi,
>>>> I have noted that Qemu VGA and serial console with EFI BIOS stopped  
>>>> working in
>>>> 0.14.0 (and in latest development snapshot is still not working).  
>>>> Everything was
>>>> fine in 0.13.0. However EFI BIOS itself is able to load kernel if it was
>>>> properly configured on used disk image. The only effect is that  
>>>> neither VGA nor
>>>> serial console is not functioning. After short investigation I have  
>>>> discovered
>>>> that this functionality was broken by this commit:
>>>>
>>>> commit 9bb3358627d87d8de25fb41b7276575539d799a7
>>>> Author: Isaku Yamahata <yamahata@valinux.co.jp>
>>>> Date:   Fri Nov 19 18:56:02 2010 +0900
>>>>
>>>> Do you have any idea how this change could affect EFI consoles?
>>>>
>>>>         
>>> After further investigation I have found that the following patch provides
>>> a workaround for the problem, may be it could be useful for somebody who
>>> is more familiar with Qemu PCI code:
>>>
>>> diff --git a/hw/pci.c b/hw/pci.c
>>> index 8b76cea..06dd7ab 100644
>>> --- a/hw/pci.c
>>> +++ b/hw/pci.c
>>> @@ -162,9 +162,11 @@ void pci_device_reset(PCIDevice *dev)
>>>     pci_update_irq_status(dev);
>>>     pci_device_deassert_intx(dev);
>>>     /* Clear all writeable bits */
>>> +#if 0
>>>     pci_word_test_and_clear_mask(dev->config + PCI_COMMAND,
>>>                                  pci_get_word(dev->wmask + PCI_COMMAND) |
>>>                                  pci_get_word(dev->w1cmask + PCI_COMMAND));
>>> +#endif
>>>     pci_word_test_and_clear_mask(dev->config + PCI_STATUS,
>>>                                  pci_get_word(dev->wmask + PCI_STATUS) |
>>>                                  pci_get_word(dev->w1cmask + PCI_STATUS));
>>>
>>> Best regards,
>>> Artyom.
>>>
>>>       
>> -- 
>> yamahata
>>
>>