Re: [PATCH v3 06/17] hw/sd/sdcard: Do not store vendor data on block drive (CMD56)

On Tue, Jul 09, 2024 at 05:38:54PM -0300, Fabiano Rosas wrote: > Philippe Mathieu-Daudé <philmd(a)linaro.org&gt; writes: > > > "General command" (GEN_CMD, CMD56) is described as: > > > > GEN_CMD is the same as the single block read or write > > commands (CMD24 or CMD17). The difference is that [...] > > the data block is not a memory payload data but has a > > vendor specific format and meaning. > > > > Thus this block must not be stored overwriting data block > > on underlying storage drive. Keep it in a dedicated > > 'vendor_data[]' array. > > > > Signed-off-by: Philippe Mathieu-Daudé <philmd(a)linaro.org&gt; > > Tested-by: Cédric Le Goater <clg(a)redhat.com&gt; > > --- > > RFC: Is it safe to reuse VMSTATE_UNUSED_V() (which happens > > to be the same size)? > > Hi, sorry it took some time to get to this, I had just left for vacation > when you first posted. And I totally overlooked there's the email.. until you replied. Welcome back.

> > I think it's ok: > > { > "field": "unused", > "version_id": 1, > "field_exists": false, > "size": 512 > }, > > vs. > > { > "field": "vendor_data", > "version_id": 0, > "field_exists": false, > "num": 512, > "size": 1 > }, > > The unused field was introduced in 2016 so there's no chance of > migrating a QEMU that old to/from 9.1. What happens if an old qemu 9.0 sends rubbish here to a new QEMU, while the new QEMU would consider it meaningful data?