This dd flag ensures that the requested size
is retrieved from pipes or special filesystems (if available).
Without this flag, on multi-core systems,
Piped or special filesystem data can be truncated
when a size greater than PIPE_BUF is requested.
Fixes: FS#3494
Fixes: 7557e7f ("package/base-files: caldata: work around dd's
limitation")
Cc: Thibaut VARÈNE <hacks@slashdirt.org>
Signed-off-by: John Thomson <git@johnthomson.fastmail.com.au>
d82c191283