X-Git-Url: http://git.jankratochvil.net/?p=badblock-guess.git;a=blobdiff_plain;f=README;h=87a3a1de5c8d114797a202fe1df3494ee9250463;hp=b02fc61e95411bfb70ea8a4fe699a2ec67cc7247;hb=refs%2Fheads%2Fmaster;hpb=ad1f5c98ae9185db345a6f3f923941771e4c7bb5

diff --git a/README b/README
index b02fc61..87a3a1d 100644
--- a/README
+++ b/README
@@ -56,10 +56,15 @@ Possible device cases (watch out for <src_dev> vs. <dst_dev> differences!):
 		drive in the system with the exactly same partition size is
 		recommended
 
-	<dst_dev> is a file: File must exist but it will be enlarged when
-		needed. Commands:
-			rm -f /tmp/hdc1.img; touch /tmp/hdc1.img
-		are recommended to specify file "/tmp/hdc1.img" for <dst_dev>
+	<dst_dev> is a file: File must exist and it must be at least the size
+		as <src_dev>. If it is larger, the trailing data will remain
+		unchanged. You can create blank file of size 123456789 by:
+			dd if=/dev/zero of=/tmp/outimg bs=1 count=1 seek=$[123456789-1]
+		The size of the original <src_dev> can be queried by:
+			hdparm -g <src_dev>
+		Be aware the size "sectors" is incorrectly the size in bytes,
+		depending on your Linux kernel version. dd(1) command above
+		requires the bytes size (use "bs=512" to use sectors value).
 
 All the numbers are always expressed as sector (that means 512 bytes)
 number/count!