Bug#488022: New findings.

[Mark Hobley <markhobley@yahoo.co.uk>]

Raúl Sánchez Siles <rsanchezs@infoglobal.es> wrote:

Make paravirt feature depends on 586/pentium (upstream), since not all 486 
support the cpuid needed infrastructure, again upstream advice would be 
needed.

Disable paravirtualization in Debian kernel for 486. This is somewhat 
thorny. Is paravirtualization absolutely needed on this architecture flavour?

Drop support for processors without cpuid, this include most low-end 
embedded/industrial 486 processors.

I think the problem here, is that we should not be making decisions based on "cpuid". It would be far better to utilize features based on build options.

The problem with cpuid, is that you can potentially have binary code that tests ok on one computer, but behaves differently on another. There are a whole lot of headaches relating to this, especially in organizations that have different processors in different machines, but the machines are all supposed to be compatible with each other.

(I don't recommend the use of Processor Supplementary Instructions and Processor Supplementary Features at all.)

if cpuid="Microsoft Sales Laptop" then
  crashes=minimal_except_when_bill_gates_is_on_television
else
  # Customers computer
  random_crash_with("Blue Screen of Death")
endif

It would be far better to let the system installer choose which features to use at build time. Power to the administrator! :)

Mark.