Re: Verbosity during boot

[Jan Beulich <jbeulich@xxxxxxxx>]

On 27.02.2025 21:38, Andrew Cooper wrote:
> I've raised this during review before, but:
> 
>> (XEN) [    1.209230] AMD-Vi: IOMMU Extended Features:
>> (XEN) [    1.213998] - Peripheral Page Service Request
>> (XEN) [    1.218849] - x2APIC
>> (XEN) [    1.221536] - NX bit
>> (XEN) [    1.224221] - Invalidate All Command
>> (XEN) [    1.228297] - Guest APIC
>> (XEN) [    1.236062] - Performance Counters
>> (XEN) [    1.244692] - Host Address Translation Size: 0x2
>> (XEN) [    1.254547] - Guest Address Translation Size: 0
>> (XEN) [    1.264313] - Guest CR3 Root Table Level: 0x1
>> (XEN) [    1.273925] - Maximum PASID: 0xf
>> (XEN) [    1.282338] - SMI Filter Register: 0x1
>> (XEN) [    1.291241] - SMI Filter Register Count: 0x2
>> (XEN) [    1.300607] - Guest Virtual APIC Modes: 0
>> (XEN) [    1.309655] - Dual PPR Log: 0x2
>> (XEN) [    1.317801] - Dual Event Log: 0x2
>> (XEN) [    1.326078] - Secure ATS
>> (XEN) [    1.333490] - User / Supervisor Page Protection
>> (XEN) [    1.342892] - Device Table Segmentation: 0x3
>> (XEN) [    1.351981] - PPR Log Overflow Early Warning
>> (XEN) [    1.361040] - PPR Automatic Response
>> (XEN) [    1.369341] - Memory Access Routing and Control: 0x1
>> (XEN) [    1.379012] - Block StopMark Message
>> (XEN) [    1.387273] - Performance Optimization
>> (XEN) [    1.395637] - MSI Capability MMIO Access
>> (XEN) [    1.404138] - Guest I/O Protection
>> (XEN) [    1.412042] - Host Access
>> (XEN) [    1.419105] - Enhanced PPR Handling
>> (XEN) [    1.427008] - Attribute Forward
>> (XEN) [    1.434494] - Host Dirty
>> (XEN) [    1.441308] - Virtualized IOMMU
>> (XEN) [    1.448699] - VMGuard I/O Support
>> (XEN) [    1.456345] - VM Table Size: 0x2
>> (XEN) [    1.491312] AMD-Vi: IOMMU 0 Enabled.
>> (XEN) [    1.499087] AMD-Vi: IOMMU 1 Enabled.
>> (XEN) [    1.506835] AMD-Vi: IOMMU 2 Enabled.
>> (XEN) [    1.514554] AMD-Vi: IOMMU 3 Enabled.
>> (XEN) [    1.522452] I/O virtualisation enabled
> 
> Lots of that information is not actually useful, not even for
> developers.

"Lots" != "all" (or maybe you meant all without saying so). Then what we'd
need are criteria by which to judge what to log and and what to omit from
logging.

>  What's worse is that this is a release build of Xen and it
> still takes 0.3s to print the feature list alone.

With a serial console, I expect? Or with us still wrongly using UC accesses
to VGA memory?

Jan