Re: [Xen-devel] [PATCH] Disable SMP on the MacBook by default

[gimli <gimli@xxxxxxxxxxxxxx>]

I had also many crashes with xen until. I did some search on google and found
a patch on the xen ml for the bridging code in linux which cused the crashes.
Have atached the patch.

cu

Edgar (gimli) Hucek

gimli schrieb:
> Marco Gerards schrieb:
>> "Ian Pratt" <m+Ian.Pratt@xxxxxxxxxxxx> writes:
>>
>> [...]
>>
>>>> The SMP issue can be avoided from GRUB when you press the "right
>>>> arrow" key instead of "enter" to boot.  Someone mentioned this on the
>>>> mailinglist, perhaps that is why you mixed up the two?
>>> This does kinda suggest that a further Grub patch might be part of the
>>> solution, no?
>> This is something I looked at, of course.  The GRUB code doesn't make
>> a difference between "right arrow" and return.  Besides that, it
>> doesn't work with the timeout either.
> 
> Hm... The strange thing is, hitting the "Return" key crashed xen every time.
> Using the "Rigth arrow" key made xen bootable evry time from grub. So there 
> must
> be a difference.
> 
>>> Are there any issues with SMP linux 2.6.16 at all?
>> No, unless you disable ACPI.
>>
>> The FreeBSD and NetBSD hackers have encountered the same problem.
>> They were not able to come up with a patch yet.
>>
>>> Any idea what's going on?
>> The second core can not be initialized because the INIT IPI does not
>> arrive.  It only happens on the MacBook and not on the desktop Intel
>> Macs.  On the MacBook the second core is put into deep sleep mode.  It
>> should get out of sleep mode when an IPI or interrupt is received.
>>
>> That does not happen.  It looks like the keyboard interrupt does
>> wakeup the second core, after which the IPI is received.
>>
>> The annoying thing is that both the keyboard handling and ACPI on the
>> Intel Mac is a big mess.  There are a lot of bugs.  It could also be a
>> bug in the processor itself.  The reason why Windows and Linux work is
>> that the ACPI interpreter is used, perhaps this also has a side effect
>> of waking up the second core.
>>
>>> What are distros link Ubuntu using for booting on MacBook? Do they go
>>> with bootcamp/grub, or elilo?
>> Sorry, I am not sure what you mean.  English is not my native
>> language.  Do you mean which bootloaders they use by default?
>>
>> When I was installing Ubuntu for the first time on the MacBook, it
>> tried installing GRUB and failed.  First I tried lilo which worked.
>> Later I started using GRUB.  I haven't seen ELILO being used anywhere.
> 
> I use the patched grub and elilo.
> 
>> --
>> Marco
>>
>>
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>> http://lists.xensource.com/xen-devel
>>
> 
> 
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> 

--- linux-2.6.16.orig/include/linux/netfilter_bridge.h
+++ linux-2.6.16/include/linux/netfilter_bridge.h
@@ -73,14 +73,14 @@ void nf_bridge_maybe_copy_header(struct 
                        memcpy(skb->data - 18, skb->nf_bridge->data, 18);
                        skb_push(skb, 4);
                } else
-                       memcpy(skb->data - 16, skb->nf_bridge->data, 16);
+                       memcpy(skb->data - 14, skb->nf_bridge->data, 14);
        }
 }
 
 static inline
 void nf_bridge_save_header(struct sk_buff *skb)
 {
-        int header_size = 16;
+        int header_size = 14;
 
        if (skb->protocol == __constant_htons(ETH_P_8021Q))
                header_size = 18;

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