In practice, there is no such thing as a real 64bit system without
APICs.  (PVH style virtual environments, sure, but they don't end up here).

The suggestion to try and use noapic only makes a bad situation worse.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
---
CC: Jan Beulich <JBeulich@suse.com>
CC: Roger Pau Monné <roger.pau@citrix.com>
CC: Wei Liu <wl@xen.org>
CC: Ian Jackson <iwj@xenproject.org>

I wanted to have enough time to drop all of the pre-APIC infrastructure, but
that is a massive can of decades-old-worms.  For 4.15, suffice just to to
prevent misleading users more than necessary.
---
 xen/arch/x86/io_apic.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/xen/arch/x86/io_apic.c b/xen/arch/x86/io_apic.c
index e66fa99ec7..e93265f379 100644
--- a/xen/arch/x86/io_apic.c
+++ b/xen/arch/x86/io_apic.c
@@ -1994,8 +1994,7 @@ static void __init check_timer(void)
         return;
     }
     printk(" failed :(.\n");
-    panic("IO-APIC + timer doesn't work!  Boot with apic_verbosity=debug "
-          "and send a report.  Then try booting with the 'noapic' option\n");
+    panic("IO-APIC + timer doesn't work!  Boot with apic_verbosity=debug and send a report\n");
 }
 
 /*
-- 
2.11.0

On 27.01.2021 20:49, Andrew Cooper wrote:
> In practice, there is no such thing as a real 64bit system without
> APICs.  (PVH style virtual environments, sure, but they don't end up here).
> 
> The suggestion to try and use noapic only makes a bad situation worse.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>

Acked-by: Jan Beulich <jbeulich@suse.com>

Jan Beulich writes ("Re: [PATCH for-4.15] x86/boot: Drop 'noapic' suggestion from check_timer()"):
> On 27.01.2021 20:49, Andrew Cooper wrote:
> > In practice, there is no such thing as a real 64bit system without
> > APICs.  (PVH style virtual environments, sure, but they don't end up here).
> > 
> > The suggestion to try and use noapic only makes a bad situation worse.
> > 
> > Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
> 
> Acked-by: Jan Beulich <jbeulich@suse.com>

Release-Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>

Not sure if this is a bugfix but it is a change to a message so fine.

Ian.

On 28/01/2021 14:57, Ian Jackson wrote:
> Jan Beulich writes ("Re: [PATCH for-4.15] x86/boot: Drop 'noapic' suggestion from check_timer()"):
>> On 27.01.2021 20:49, Andrew Cooper wrote:
>>> In practice, there is no such thing as a real 64bit system without
>>> APICs.  (PVH style virtual environments, sure, but they don't end up here).
>>>
>>> The suggestion to try and use noapic only makes a bad situation worse.
>>>
>>> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
>> Acked-by: Jan Beulich <jbeulich@suse.com>
> Release-Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>

Thanks.

> Not sure if this is a bugfix but it is a change to a message so fine.

It was one of many delaying factors with the "Xen doesn't boot on modern
Intel client CPUs".

~Andrew