[PATCH 02/14] bootm: Change incorrect 'unsupported' error

[Simon Glass]

Hi Heinrich,

On Fri, 9 Sept 2022 at 09:33, Heinrich Schuchardt <xypron.glpk at gmx.de> wrote:
>
>
>
> Am 9. September 2022 17:17:49 MESZ schrieb Simon Glass <sjg at chromium.org>:
> >At present when bootm fails, it says:
> >
> >    subcommand not supported
> >
> >and then prints help for the bootm command. This is not very useful, since
> >generally the error is related to something else, such as fixups failing.
> >It is quite confusing to see this in a test run.
> >
> >Change the error and show the error code.
> >
> >We could update the OS functions to return -ENOSYS when they do not
> >support the bootm subcommand. But this involves some thought since this is
> >arch-specific code and proper errno error codes are not always returned.
> >Also, with the code as is, all required subcommands are of course
> >supported - a problem would only come if someone added a new one or
> >removed support for one from an existing OS. Therefore it seems better to
> >leave that sort of effort for when our bootm tests are improved.
> >
> >Signed-off-by: Simon Glass <sjg at chromium.org>
> >---
> >
> > boot/bootm.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> >diff --git a/boot/bootm.c b/boot/bootm.c
> >index f6713807fda..ed6b489c4b3 100644
> >--- a/boot/bootm.c
> >+++ b/boot/bootm.c
> >@@ -790,7 +790,7 @@ int do_bootm_states(struct cmd_tbl *cmdtp, int flag, int argc,
> >
> >       /* Check for unsupported subcommand. */
> >       if (ret) {
> >-              puts("subcommand not supported\n");
> >+              printf("subcommand failed (err=%d)\n", ret);
>
> Return codes are only interpretable by developers. We have a function to convert errno to a string.
>
> For the average user it would be helpful to know which  (sub-)command failed especially if this boot command is executed in an automated way.

I don't disagree, but:
1. The error strings add to code size, about 5KB or so
2. For devs the error number is much easier to use
3. For bug reports the error number is better too IMO
4. As per the commit message, we don't have a consistent way for
subcommands to report errors

So I think this patch is an improvement, in that it actually says what
is happening (rather than mostly saying something that is untrue) and
does not increase code size much.

I wonder if we should have a way to show an error number + string in printf()?

printf("subcommand failed (%pE)\n", ret);

I don't fully understand how we allow things after %p without
ambiguity...do you know?

Regards,
Simon