fix region offset handling (#485)

The specification states that the region offset given in the region info should
be used as the "offset" when mmap()ing the region from the client side. However,
the library instead implemented a fixed offset scheme  similar to that of vfio -
and no clients actually set up the file like that.

Instead, let servers define their own offsets, and pass them through to clients
as is. It's up to the server to decide how its backing file or files is
organized.

Signed-off-by: John Levon <john.levon@nutanix.com>
Reviewed-by: Thanos Makatos <thanos.makatos@nutanix.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/samples/gpio-pci-idio-16.c b/samples/gpio-pci-idio-16.c
index f9caa04..7bffb5e 100644
--- a/samples/gpio-pci-idio-16.c
+++ b/samples/gpio-pci-idio-16.c
@@ -205,13 +205,13 @@ main(int argc, char *argv[])
     vfu_pci_set_id(vfu_ctx, 0x494f, 0x0dc8, 0x0, 0x0);
 
     ret = vfu_setup_region(vfu_ctx, VFU_PCI_DEV_BAR2_REGION_IDX, 0x100,
-                           &bar2_access, VFU_REGION_FLAG_RW, NULL, 0, -1);
+                           &bar2_access, VFU_REGION_FLAG_RW, NULL, 0, -1, 0);
     if (ret < 0) {
         err(EXIT_FAILURE, "failed to setup region");
     }
 
     ret = vfu_setup_region(vfu_ctx, VFU_PCI_DEV_MIGR_REGION_IDX, migr_size,
-                           NULL, VFU_REGION_FLAG_RW, NULL, 0, -1);
+                           NULL, VFU_REGION_FLAG_RW, NULL, 0, -1, 0);
     if (ret < 0) {
         err(EXIT_FAILURE, "failed to setup migration region");
     }