[Pdbg] [PATCH 1/2] libpdbg: Check if scom controllers are exposed

[Alistair Popple]

Thanks Rashmica!

On Tuesday, 8 May 2018 10:11:25 AM AEST Rashmica Gupta wrote:
> If CONFIG_SCOM_DEBUGFS is not set in the running kernel then
> the scom controllers are not exposed and so using getscom
> won't work. Add check for /sys/kernel/debug/powerpc/scom to
> give a more useful error message.
> 
> Signed-off-by: Rashmica Gupta <rashmica.g at gmail.com>
> ---
>  libpdbg/host.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/libpdbg/host.c b/libpdbg/host.c
> index f43b355..cf71e5c 100644
> --- a/libpdbg/host.c
> +++ b/libpdbg/host.c
> @@ -95,6 +95,13 @@ static int host_pib_probe(struct pdbg_target *target)
>  	if (chip_id == -1)
>  		goto out;
>  
> +	/* This check should probably be done earlier */
> +	if (access(XSCOM_BASE_PATH, F_OK) == -1)
> +	{
> +		fprintf(stderr, "Can not access %s. ", XSCOM_BASE_PATH);
> +		fprintf(stderr, "Is CONFIG_SCOM_DEBUGFS set?\n");

Looks good but we should add a `goto out;` here so that the probing fails.
Ideally I'd like not to print anything in the probe/library functions but this
makes error reporting hard so I am ok with it for the moment. I know Amitay was
looking at improving the way we handle output/error reporting so we can figure
it out then.

- Alistair

> +	}
> +
>  	if (asprintf(&access_fn, "%s/%08d/access", XSCOM_BASE_PATH, chip_id) < 0)
>  		goto out;
>  
>