add support for specifying MSI cap in dev welcome

corundum/corundum_verilator.cpp

@@ -385,6 +385,7 @@ int main(int argc, char *argv[])
     di.pci_class = 0x02;
     di.pci_subclass = 0x00;
     di.pci_revision = 0x00;
+    di.pci_msi_nvecs = 32;
 
     if (nicsim_init(&di, "/tmp/cosim-pci", "/dev/shm/dummy_nic_shm")) {
         return EXIT_FAILURE;

dummy_nic/dummy_nic.c

@@ -124,6 +124,7 @@ int main(int argc, char *argv[])
     di.pci_class = 0x02;
     di.pci_subclass = 0x00;
     di.pci_revision = 0x00;
+    di.pci_msi_nvecs = 0x00;
 
     if (nicsim_init(&di, "/tmp/cosim-pci", "/dev/shm/dummy_nic_shm")) {
         return EXIT_FAILURE;

proto/cosim_pcie_proto.h

@@ -59,6 +59,8 @@ struct cosim_pcie_proto_dev_intro {
     uint8_t pci_subclass;
     /* PCI revision */
     uint8_t pci_revision;
+    /* PCI number of MSI vectors */
+    uint8_t pci_msi_nvecs;
 } __attribute__((packed));