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SubjectRe: [PATCH] tools/bootconfig: Fix wrong __VA_ARGS__ usage
Date
Masami Hiramatsu <mhiramat@kernel.org> writes:
> Since printk() wrapper macro uses __VA_ARGS__ without
> "##" prefix, it causes a build error if there is no
> variable arguments (e.g. only fmt is specified.)
> To fix this error, use ##__VA_ARGS__ instead of
> __VAR_ARGS__.
>
> Fixes: 950313ebf79c ("tools: bootconfig: Add bootconfig command")
> Reported-by: Michael Ellerman <mpe@ellerman.id.au>
> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
> ---
> tools/bootconfig/include/linux/printk.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)

Thanks that builds for me.

The output when adding to a fresh initrd is a bit confusing though, eg:

$ ./bootconfig -a samples/good-simple.bconf initrd.img
Apply samples/good-simple.bconf to initrd.img
Number of nodes: 13
Size: 120 bytes
Checksum: 9036
checksum error: 0 != 444373994
$ echo $?
0

ie. the checksum error.

That's because although delete_xbc() does:

pr_output = 0;
size = load_xbc_from_initrd(fd, &buf);

in load_xbc_from_initrd() the error message is printed with printf, not
printk, so it's not controlled by pr_output:

printf("checksum error: %d != %d\n", csum, rcsum);

Switching that line to printk fixes it, ie. makes the checksum error go
away, but it seems a bit odd to be using printk in userspace code.

cheers

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