[PATCH] lib: add PL011 to _CID whitelist

[Alex Hung]

On Thu, Nov 8, 2018 at 8:18 AM Al Stone <al.stone at linaro.org> wrote:
>
> On 11/7/18 1:51 AM, ivanhu wrote:
> > I was in UEFI plugfest two, at first I think we can whitelist this ID, but
> >
> > ACPI specification do define the type of the IDs,
> >
> > A valid PNP ID must be of the form "AAA####" where A is an uppercase
> > letter and # is a hex
> > digit. A valid ACPI ID must be of the form "NNNN####" where N is an
> > uppercase letter or a
> > digit ('0'-'9') and # is a hex digit.
> >
> > "PL011" indeed not follow the ACPI specification.
> >
> > They know it is not following the ACPI specification, they cannot change
> > it because the legacy machine use it.
> >
> > I think it maybe good idea let FWTS to spot all failures which not
> > following the ACPI specification, even if it is in used.
> >
> > Any thoughts?
>
> Section 6.1.2 of the spec is pretty clear on what is allowed for _CID; 'PL011'
> is not allowed.  It is not in the PCI or ACPI ID registries, either.
>
> I have seen this used in some very, very old firmware, and the vendor that made
> the firmware was forced to correct it as soon as I saw it.  So, that firmware
> has since been corrected, and there is no excuse for it to still be in use, even
> on a "legacy system."
>
> The value should be 'ARMH0011', so this is broken firmware, and if the kernel is
> accepting 'PL011', that's wrong, too.
>
> Vendors should not be using this at all.  The test should fail.

Thanks Al for the clarification. Now I know what to ask vendors to change to.

>
> > Cheers,
> >
> > Ivan
> >
> > On 11/7/18 12:13 PM, Alex Hung wrote:
> >> When attending UEFI Plugfest, a vendor suggested _CID PL011 is used in
> >> the field, and this ID is added to a whitelist to avoid false positive.
> >>
> >> Signed-off-by: Alex Hung <alex.hung at canonical.com>
> >> ---
> >>  src/lib/src/fwts_acpi_object_eval.c | 4 ++++
> >>  1 file changed, 4 insertions(+)
> >>
> >> diff --git a/src/lib/src/fwts_acpi_object_eval.c b/src/lib/src/fwts_acpi_object_eval.c
> >> index 0bc0f134..95f7df76 100644
> >> --- a/src/lib/src/fwts_acpi_object_eval.c
> >> +++ b/src/lib/src/fwts_acpi_object_eval.c
> >> @@ -968,6 +968,10 @@ bool fwts_method_valid_HID_string(char *str)
> >>              return true;
> >>      }
> >>
> >> +    /* PL011 is used out there, so whitelist it */
> >> +    if (strlen(str) == 5 && !strncmp(str, "PL011", 5))
> >> +            return true;
> >> +
> >>      return false;
> >>  }
> >>
> >
> >
>
>
> --
> ciao,
> al
> -----------------------------------
> Al Stone
> Software Engineer
> Linaro Enterprise Group
> al.stone at linaro.org
> -----------------------------------
>
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-- 
Cheers,
Alex Hung