dmesg pre-init items of possible note

[khionu]

Opening an issue just to track the pre-init dmesg items I spot that may be hints to other issues or just worth addressing at some point

• ACPI: MPS support code is not built-in, using acpi=off or acpi=noirq or pci=noacpi may have problem
• DMI not present or invalid
• tsc: Fast TSC calibration failed
• Kernel parameter elevator= does not have effect anymore. Please use sysfs to set IO scheduler for individual devices
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