Re: [PATCH v2 1/4] usb: early: Avoid using DbC if already enabled

[Connor Davis]

On 5/17/21 8:13 AM, Jan Beulich wrote:
> On 17.05.2021 15:48, Connor Davis wrote:
> > On 5/17/21 3:32 AM, Jan Beulich wrote:
> > > On 14.05.2021 02:56, Connor Davis wrote:
> > > > Check if the debug capability is enabled in early_xdbc_parse_parameter,
> > > > and if it is, return with an error. This avoids collisions with whatever
> > > > enabled the DbC prior to linux starting.
> > > Doesn't this go too far and prevent use even if firmware (perhaps
> > > mistakenly) left it enabled?
> > Yes, but how is one supposed to distinguish the broken firmware and
> > non-broken
> >
> > firmware cases?
> Well, a first step might be to only check if running virtualized.
> And then if your running virtualized, there might be a way to
> inquire the hypervisor?

Right, but if it was enabled by something other than a hypervisor,

or you're not running virtualized, how do you distinguish then? IMO

the proper thing to do in any case is to simply not use the DbC in linux.

Thanks,

Connor