vhost-user requires -object memory-backend-*,share=on option so that QEMU uses mmap(MAP_SHARED) on guest RAM that is shared with the vhost-user device backend process. This is needed so the QEMU process sees changes made by the vhost-user device backend process, and vice versa.
Today QEMU and the vhost-user device process will start up and then fail with a confusing error message if the user forgot to specify share=on. This patch series adds a warning letting the user know that share=on is required. Stefan Hajnoczi (3): tests/qtest/vhost-user-test: use share=on with memfd memory: add memory_region_is_mapped_shared() vhost-user: warn when guest RAM is not shared include/exec/memory.h | 11 +++++++++++ hw/virtio/vhost-user.c | 20 ++++++++++++++++---- softmmu/memory.c | 6 ++++++ tests/qtest/vhost-user-test.c | 2 +- 4 files changed, 34 insertions(+), 5 deletions(-) -- 2.29.2