fix compile on riscv

kernel/src/syscall/custom.rs

@@ -2,16 +2,20 @@
 use rcore_memory::memory_set::handler::Linear;
 use rcore_memory::memory_set::MemoryAttr;
 use super::*;
-use crate::drivers::bus::pci;
 
+#[cfg(target_arch = "x86_64")]
 pub fn sys_map_pci_device(vendor: usize, product: usize) -> SysResult {
+    use crate::drivers::bus::pci;
     info!(
         "map_pci_device: vendor: {}, product: {}",
         vendor, product
     );
-    if let Some(tag) = pci::find_device(vendor as u32, product as u32) {
+    let tag = pci::find_device(vendor as u32, product as u32)
+        .ok_or(SysError::ENOENT)?;
     // Get BAR0 memory
-        if let Some((base, len)) = unsafe { tag.get_bar_mem(0) } {
+    let (base, len) = unsafe { tag.get_bar_mem(0) }
+        .ok_or(SysError::ENOENT)?;
+
     let mut proc = process();
     let virt_addr = proc.memory_set.find_free_area(0, len);
     let attr = MemoryAttr::default().user();
@@ -23,10 +27,9 @@ pub fn sys_map_pci_device(vendor: usize, product: usize) -> SysResult {
         "pci",
     );
     Ok(virt_addr)
-        } else {
-            Err(SysError::ENOENT)
-        }
-    } else {
-        Err(SysError::ENOENT)
-    }
+}
+
+#[cfg(not(target_arch = "x86_64"))]
+pub fn sys_map_pci_device(vendor: usize, product: usize) -> SysResult {
+    Err(SysError::ENOSYS)
 }