Re: [Xen-devel] [PATCH] x86: suppress warning messages on IO-APIC-less systems

[Keir Fraser <keir@xxxxxxx>]

On 17/04/2012 13:58, "Jan Beulich" <JBeulich@xxxxxxxx> wrote:

> Each call to mp_register_gsi() so far produced two warnings (about not
> being able to find the corresponding IO-APIC pin).
> 
> However, we should use the provided information for setting the ELCR
> correctly (we might want to even do this when there is an IO-APIC, if
> was absolutely certain that all machines really have this register
> [and specifically not some other device at the two I/O ports in
> question]). It is in any case questionable that we allow Dom0 to set
> this register - it could particularly be the interrupt of a plug-in
> serial port card that might not work due to this. The problem is that
> all Dom0 kernels to date do so, hence we can't simply #GP on such an
> access (which would be the result if we disallowed access to the port
> as we should have done from the beginning).
> 
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

Acked-by: Keir Fraser <keir@xxxxxxx>

> --- a/xen/arch/x86/mpparse.c
> +++ b/xen/arch/x86/mpparse.c
> @@ -1034,6 +1034,21 @@ int mp_register_gsi (u32 gsi, int trigge
> return gsi;
>  #endif
>  
> + if (!nr_ioapics) {
> +  unsigned int port = 0x4d0 + (gsi >> 3);
> +  u8 val;
> +
> +  if (!platform_legacy_irq(gsi))
> +   return -EINVAL;
> +  val = inb(port);
> +  if (triggering)
> +   val |= 1 << (gsi & 7);
> +  else
> +   val &= ~(1 << (gsi & 7));
> +  outb(val, port);
> +  return 0;
> + }
> +
> ioapic = mp_find_ioapic(gsi);
> if (ioapic < 0) {
> printk(KERN_WARNING "No IOAPIC for GSI %u\n", gsi);
> 
> 
> 
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