Re: [Qemu-devel] [PATCH v2 4/5] tpm: add CRB device

[Eduardo Habkost <ehabkost@redhat.com>]

On Fri, Jan 19, 2018 at 12:10:03PM -0500, Stefan Berger wrote:
> On 01/19/2018 09:11 AM, Marc-André Lureau wrote:
> > tpm_crb is a device for TPM 2.0 Command Response Buffer (CRB)
> > Interface as defined in TCG PC Client Platform TPM Profile (PTP)
> > Specification Family “2.0” Level 00 Revision 01.03 v22.
> > 
> > The PTP allows device implementation to switch between TIS and CRB
> > model at run time, but given that CRB is a simpler device to
> > implement, I chose to implement it as a different device.
> > 
> > The device doesn't implement other locality than 0 for now (my laptop
> > TPM doesn't either, so I assume this isn't so bad)
> > 
> > The command/reply memory region is statically allocated after the CRB
> > registers address TPM_CRB_ADDR_BASE + sizeof(struct crb_regs) (I
> > wonder if the BIOS could or should allocate it instead, or what size
> > to use, again this seems to fit well expectations)
> 
> I removed this last sentence now. It's at the right location.
> 
> > 
> > The PTP doesn't specify a particular bus to put the device. So I added
> > it on the system bus directly, so it could hopefully be used easily on
> > a different platform than x86. Currently, it fails to init on piix,
> > because error_on_sysbus_device() check. The check may be changed in a
> > near future, see discussion on the qemu-devel ML.
> 
> I think this has to be solved. So I remove these last 2 sentences. I'll have
> to wait until that other patch series from Eduard is merged since it doesn't
> start yet.

The series was just merged to master.  It's possible to make a
machine accept the new device using
machine_class_allow_dynamic_sysbus_dev(), now.

However, is it really necessary to make it a sysbus device?
Having bus-less devices was not possible in the past, but it is
possible today.

-- 
Eduardo