diff --git a/osbase/blockdev/blockdev_linux_test.go b/osbase/blockdev/blockdev_linux_test.go
index 9cbf027..b61c1ee 100644
--- a/osbase/blockdev/blockdev_linux_test.go
+++ b/osbase/blockdev/blockdev_linux_test.go
@@ -6,6 +6,7 @@
 package blockdev
 
 import (
+	"io"
 	"os"
 	"testing"
 
@@ -66,6 +67,98 @@
 		t.Fatalf("Failed to create file: %v", err)
 	}
 	defer os.Remove("/tmp/testfile")
+	defer blk.Close()
 
 	ValidateBlockDev(t, blk, fileBlockCount, fileBlockSize, fileBlockSize)
+
+	// ReadFromAt
+	srcFile, err := os.Create("/tmp/copysrc")
+	if err != nil {
+		t.Fatalf("Failed to create source file: %v", err)
+	}
+	defer os.Remove("/tmp/copysrc")
+	defer srcFile.Close()
+	var size int64 = fileBlockSize * fileBlockCount
+	readFromAtTests := []struct {
+		name   string
+		offset int64
+		data   string
+		limit  int64
+		ok     bool
+	}{
+		{"empty start", 0, "", -1, true},
+		{"empty end", size, "", -1, true},
+		{"normal", 3, "abcdef", -1, true},
+		{"limited", 3, "abcdef", 4, true},
+		{"large limit", 3, "abcdef", size, true},
+		{"ends at the end", size - 4, "abcd", -1, true},
+		{"ends past the end", size - 4, "abcde", -1, false},
+		{"ends past the end with limit", size - 4, "abcde", 10, false},
+		{"offset negative", -1, "abc", -1, false},
+		{"starts at the end", size, "abc", -1, false},
+		{"starts past the end", size + 4, "abc", -1, false},
+	}
+	for _, tt := range readFromAtTests {
+		t.Run("readFromAt "+tt.name, func(t *testing.T) {
+			checkBlockDevOp(t, blk, func(content []byte) {
+				// Prepare source file
+				err = srcFile.Truncate(0)
+				if err != nil {
+					t.Fatalf("Failed to truncate source file: %v", err)
+				}
+				_, err = srcFile.WriteAt([]byte("123"+tt.data), 0)
+				if err != nil {
+					t.Fatalf("Failed to write source file: %v", err)
+				}
+				_, err = srcFile.Seek(3, io.SeekStart)
+				if err != nil {
+					t.Fatalf("Failed to seek source file: %v", err)
+				}
+
+				// Do ReadFromAt
+				r := io.Reader(srcFile)
+				lr := &io.LimitedReader{R: srcFile, N: tt.limit}
+				if tt.limit != -1 {
+					r = lr
+				}
+				n, err := blk.ReadFromAt(r, tt.offset)
+				if (err == nil) != tt.ok {
+					t.Errorf("expected error %v, got %v", tt.ok, err)
+				}
+				expectedN := 0
+				if tt.offset >= 0 && tt.offset < size {
+					c := content[tt.offset:]
+					if tt.limit != -1 && tt.limit < int64(len(c)) {
+						c = c[:tt.limit]
+					}
+					expectedN = copy(c, tt.data)
+				}
+				if n != int64(expectedN) {
+					t.Errorf("got n = %d, expected %d; err: %v", n, expectedN, err)
+				}
+
+				// Check new offset
+				newOffset, err := srcFile.Seek(0, io.SeekCurrent)
+				if err != nil {
+					t.Fatalf("Failed to get source file position: %v", err)
+				}
+				newOffset -= 3
+				minOffset := n
+				maxOffset := n
+				if !tt.ok {
+					maxOffset = int64(len(tt.data))
+					if tt.limit != -1 {
+						maxOffset = min(maxOffset, tt.limit)
+					}
+				}
+				if minOffset > newOffset || newOffset > maxOffset {
+					t.Errorf("Got newOffset = %d, expected between %d and %d", newOffset, minOffset, maxOffset)
+				}
+				remaining := tt.limit - newOffset
+				if tt.limit != -1 && lr.N != remaining {
+					t.Errorf("Got lr.N = %d, expected %d", lr.N, remaining)
+				}
+			})
+		})
+	}
 }