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

[Rashmica Gupta]

On Tue, May 8, 2018 at 10:23 AM, Joel Stanley <joel at jms.id.au> wrote:
> On 8 May 2018 at 09:41, Rashmica Gupta <rashmica.g at gmail.com> 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");
>
> We're in the same boat if the user runs without sufficient permission
> (debugfs is usually not readable for normal users).

 I was thinking of adding a check to see if we have root permissions
earlier in the process. Do all things require root permission? (I've
only played around with getscom and htm so far)

>
> Perhaps the message should take that into account?
>
> Cheers,
>
> Joel