Re: [Qemu-devel] vNVRAM / blobstore design

["Michael S. Tsirkin" <mst@redhat.com>]

On Wed, Mar 27, 2013 at 11:43:53AM -0400, Kenneth Goldman wrote:
> A few comments FWIW
> 
> When I first did TPM 1.2, I stored different parts of the TPM NV data
> (permanent data, owner evict keys, defined space) in different files.  It got
> ugly and I eventually changed to one big blob, This was far more portable,
> worked better for real flash memory, etc.  It also handles integrity and/or
> encryption with less overhead.
> 
> As for encoding, I didn't bother with DER, XML, etc, as the TPM was big enough
> without importing complex parsers.  The TPM already requires marshalling and
> unmarshalling code in its native binary format for command and response
> handling, so I just reused that code.  I added version numbers and count values
> to handle changes to the format, and a hash to detect corruption.
> 
> --
> Ken Goldman   kgoldman@us.ibm.com  
> 914-945-2415 (862-2415)

Yea it's not hard to invent a random format each time we write something
on disk.

But I think ASN.1 BER will be useful to have in qemu anyway.  E.g. it's a
better format for migration than what we have now.  Once we have it in
tree re-using it seems cleaner than maintaining some per-TPM thing.

-- 
MST