On Tue, Nov 26, 2013 at 5:32 AM, Laszlo Ersek <ler...@redhat.com> wrote: > On 11/26/13 13:36, Markus Armbruster wrote: > >> Your stated purpose for multiple -pflash: >> >> This accommodates the following use case: suppose that OVMF is split in >> two parts, a writeable host file for non-volatile variable storage, and a >> read-only part for bootstrap and decompressible executable code. >> >> Such a split between writable part and read-only part makes sense to me. >> How is it done in physical hardware? Single device with configurable >> write-protect, or two separate devices? > > (Jordan could help more.) > > Likely one device that's fully writeable.
Most parts will have a dedicated read-only line. Many devices have 'block-locking' that will make some subset of blocks read-only until a reset. In addition to this, many chipsets will allow flash writes to be protected by triggering SMM when a flash write occurs. Using multiple chips are less common due to cost, but this is not a factor for QEMU. :) -Jordan
