On Mon, Nov 10, 2025 at 2:09 PM Markus Armbruster <[email protected]> wrote: > > Clément Chigot <[email protected]> writes: > > > On Mon, Nov 10, 2025 at 11:13 AM Markus Armbruster <[email protected]> > > wrote: > >> > >> Clément Chigot <[email protected]> writes: > >> > >> > This allows more flexibility to vvfat backend. The values of "Number of > >> > Heads" and "Sectors per track" are based on SD specifications Part 2. > >> > > >> > Due to the FAT architecture, not all sizes are reachable. Therefore, it > >> > could be round up to the closest available size. > >> > > >> > FAT32 has not been adjusted and thus still default to 504 Mib. > >> > > >> > For floppy, only 1440 Kib and 2880 Kib are supported. > >> > > >> > Signed-off-by: Clément Chigot <[email protected]> > >> > >> [...] > >> > >> > diff --git a/qapi/block-core.json b/qapi/block-core.json > >> > index 8a479ba090..0bcb360320 100644 > >> > --- a/qapi/block-core.json > >> > +++ b/qapi/block-core.json > >> > @@ -3478,11 +3478,17 @@ > >> > # (default: true) > >> > # (since 10.2) > >> > # > >> > +# @fat-size: size of the device in bytes. Due to FAT underlying > >> > +# architecture, this size can be rounded up to the closest valid > >> > +# size. > >> > +# (since 10.2) > >> > +# > >> > >> Can you explain again why you moved from @size to @fat-size? > > > > Just to be sure, you mean in the above comment, in the commit message or > > both ? > > Just to me, because I'm not sure I like the change, but that may well be > due to a lack of understanding of your reasons.
Naming `fat-size` instead of `size` ensures the parameter is only recognized by the vvfat backend. In particular, it will be refused by the default raw format, avoiding confusion: "-drive file=fat:<path>,size=256M" results in a 504M FAT disk truncated to 256M, raw format being implicit. "-drive file=fat:<path>,fat-size=256M" is refused. "fat-size" is unsupported by raw format. "-drive file=fat:<path>,format=vvfat,fat-size=256M" results in a 256M FAT disk. "-drive file=fat:<path>,format=vvfat,size=256M" is refused. "size" is unsupported by vvfat format.
