On Thu, Jul 11, 2019 at 12:29:30PM +0000, Safford, David (GE Global Research, US) wrote:
> Most x86 desktops and laptops have firmware TPMs which support the
> CRB interface. Unfortunately, the linux tpm_crb driver depends on
> perfectly correct ACPI tables, and there are a *lot* of systems out
> there with broken tpm_crb entries. (Not one of my five tpm_crb
> systems works with the existing driver.) While it is good to
> encourage vendors to fix their firmware, many refuse ("It works on
> Windows"), leaving users in the lurch.
>
> This patch adds a kernel parameter "tpm_crb.force=1" that works
> around the problem in every case I have tested so far. Basically
> it does two things:
> - it trusts the cmd and resp addresses in the CRB registers
> - it ignores all alleged IO resource conflicts
>
> Both workarounds make sense. If there really were an address conflict,
> or if the register values really were wrong, the device would not be
> working at all. And testing with this patch has shown that in every
> case (so far), the problem has been bogus ACPI entries.
>
> This patch is against the upstream 5.2 kernel.
>
> Signed-off-by: David Safford <david.safford@xxxxxx>
Will give a detailed review but generally we workaround firmware
issues when possible so in that way there is no argument here.
/Jarkko
