From mboxrd@z Thu Jan  1 00:00:00 1970
From: Keir Fraser <keir.xen@gmail.com>
Subject: Re: Xen randomly stuck in mdelay() during MP
 initialization
Date: Wed, 11 Jan 2012 13:28:40 +0000
Message-ID: <CB333F08.28854%keir.xen@gmail.com>
References: <CAKZ=5EUEYzopp7yOTm839ZVW3QVxRwQJDmoNr3Xc_DoBjpZP2w@mail.gmail.com>
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To: Julian Pidancet <julian.pidancet@gmail.com>, xen-devel@lists.xensource.com
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On 11/01/2012 13:06, "Julian Pidancet" <julian.pidancet@gmail.com> wrote:

> Hi,
> 
> When trying to boot xen 4.1 on new hardware, Xen become stuck in
> wakeup_secondary_cpu() in the mdelay function.
> 
>     Dprintk("Waiting for send to finish...\n");
>     timeout = 0;
>     do {
>         Dprintk("+");
>         udelay(100);
>         if ( !x2apic_enabled )
>             send_status = apic_read(APIC_ICR) & APIC_ICR_BUSY;
>     } while ( send_status && (timeout++ < 1000) );
> 
>     printk("before mdelay\n");
>     mdelay(10);
>     printk("after mdelay\n");
> 
>     Dprintk("Deasserting INIT.\n");
> 
> The hang can happen randomly with any of the CPUs to wake up and
> sometime doesn't happen at all.
> Replacing mdelay(10) with udelay(10) seems to fix the issue.

Do you see this in xen-unstable? Hopefully it is working there, and we can
simply backport the fix.

 -- Keir