Re: [PATCH 0/5] block/vvfat: introduce "size" option

[Kevin Wolf <kwolf@redhat.com>]

Am 12.11.2025 um 13:38 hat Richard W.M. Jones geschrieben:
> On Wed, Sep 03, 2025 at 09:57:16AM +0200, Clément Chigot wrote:
> > The main goal of this series is to introduce a new option "size" within
> > the vvfat backend (patch 5). It allows more control over SD cards' size.
> > The value for "Number of Heads" and "Sectors per track" are based on SD
> > specifications Part 2.
> > 
> > This series also includes minor patches:
> >  - patch 1 introduces another option to remove the Master Boot Record
> >    (this is mandatory for QNX)
> >  - patch 2-4 are minor improvements easing the introducing of "size"
> >    option
> > 
> > This was tested on with a aarch64-linux kernel taken from
> > functional/aarch64/test-virt and on aarch64-qnx over raspi4b with a
> > workaround, not included here (the SD bus must be associated to the EMMC2
> > port instead of through GPIOs).
> > 
> > Clément Chigot (5):
> >   vvfat: introduce no-mbr option
> >   vvfat: move fat_type check prior to size setup
> >   vvfat: add a define for SECTOR_SIZE
> >   vvfat: move size parameters within driver structure
> >   vvfat: add support for "size" options
> > 
> >  block/vvfat.c | 279 ++++++++++++++++++++++++++++++++++++++------------
> >  1 file changed, 213 insertions(+), 66 deletions(-)
> 
> (Thanks Markus for bringing this thread up)
> 
> I just wanted to say that a long time ago I wrote an nbdkit plugin
> that was intended as a more sane replacement for vfat.

What does it do differently from vvfat? For the read-only part, I
thought that vvfat wasn't too bad. Write support is where all the bugs
are hiding. But if you have good input, maybe vvfat could be improved.

> Since then several more nbdkit plugins have been added.  They support
> arbitrary sizes already.  The first one is the most direct replacement
> for vvfat (although it doesn't support writes to the backing
> directory, because that feature is insane).

The scenario we discussed here was explicitly read-write.

Kevin