# Test Case: Primary Plus One mkfs Blob Provider

**Test ID**: TC099-multidev-2devices  
**Category**: Multi-Device  
**Priority**: Critical

## Objective

Verify the common two-provider layout emitted directly by erofs-utils 1.8.6,
including statfs aggregation and fail-closed omission of the blob provider.

## Positive procedure

```sh
I=/root/repo22-g6/images
S=/root/repo22-g6/sources/chunk
mkdir -p /mnt/g6
kldload /root/repo22-g6/erofs.ko
mdconfig -a -t vnode -f "$I/mkfs-blob-primary.erofs" -u 90
mdconfig -a -t vnode -f "$I/mkfs-blob-slot1.blob" -u 91
mount -t erofs -o ro -o device.1=/dev/md91 /dev/md90 /mnt/g6
mount -p | grep '/mnt/g6'
df -k /mnt/g6
sha256 "$S/tc006.bin" /mnt/g6/tc006.bin
cmp "$S/tc006.bin" /mnt/g6/tc006.bin
dd if="$S/tc006.bin" of=/tmp/tc099.src bs=1 skip=28672 count=8192 2>/dev/null
dd if=/mnt/g6/tc006.bin of=/tmp/tc099.mnt bs=1 skip=28672 count=8192 2>/dev/null
cmp /tmp/tc099.src /tmp/tc099.mnt
```

The manifest reports primary blocks 1 and slot blocks 224, so `df -k` must
report 900 one-kilobyte blocks.  Metadata comes from md90; all file bytes come
from md91.

Unmount and detach both providers before the negative step.

## Missing blob option

```sh
umount /mnt/g6
mdconfig -d -u 91
mdconfig -d -u 90
mdconfig -a -t vnode -f "$I/mkfs-blob-primary.erofs" -u 90
truss -f -o /tmp/tc099-enxio.truss mount -t erofs -o ro \
  /dev/md90 /mnt/g6
tail -20 /tmp/tc099-enxio.truss
```

Mount must return exactly `ENXIO`: the 4096-byte split primary is shorter than
the declared flatdev range.

## Cleanup and zero-state check

```sh
mdconfig -d -u 90
kldunload erofs
rm -f /tmp/tc099.src /tmp/tc099.mnt
mount -p | awk '$3 == "erofs" { print }'
mdconfig -l
kldstat -n erofs 2>/dev/null || true
sysctl -n kern.geom.conftxt | grep -E 'md9[01]|erofs' || true
```

All four final outputs must be empty.