* Peter Maydell (peter.mayd...@linaro.org) wrote: > On 9 November 2018 at 17:19, Corey Minyard <cminy...@mvista.com> wrote: > > On 11/9/18 9:02 AM, Peter Maydell wrote: > >> The data provided by the caller is only the initialization > >> data. So I think the device should create its own memory > >> to copy that init data into, and migrate that ram, not > >> wherever the initialization data lives. (Currently > >> this "copy the data into our own ram" happens in the > >> smbus_eeprom_init() wrapper, but we should do it in the > >> device realize function instead.) > > > > > > That's what I would like, but should I get rid of the "DEFINE_PROP_PTR"? > > I don't know the value of creating a properly like this, since the user > > can't set it and can't see it. Plus the comments in the code say that > > it should be gotten rid of at some point. > > > > But if I store off the initialization data and keep the actual data in > > a separate memory created by the realize function, that should work > > find. > > Well, you still have to pass the init data to the device > somehow, so I think a pointer property is not a terrible > way to do that. > > >> Also there seem to be unresolved questions about what happens > >> on reset -- should the EEPROM revert back to the initial > >> contents? We don't do that at the moment, but this breaks > >> the usual QEMU pattern that reset is as if you'd just > >> completely restarted QEMU. > > > > > > I would consider this part of the hardware, like data on a disk drive, > > so it seem better to leave it alone after a reset. But it's not quite > > the same. So I'm not sure. > > That would require us to support backing it properly with a block > device, like the pflash flash devices, I think. (This would > be the long term way to be able to dump the pointer property, > in favour of a block backend property.)
There's a number of separate questions: a) Can the guest write to the EEPROM or are we just treating it as a ROM? b) If a guest writes to the EEPROM and then resets does the data stay there [I'd expect so, it's an EEPROM] c) It the guest writes to the EEPROM and then quits qemu and restarts does the data stay there? d) If the guest is migrated does it keep the data it's written - I'd say it must because otherwise it would get confused. (c) is where it starts looking like a pflash - which does get a bit messy. Dave > thanks > -- PMM -- Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
