Showing signed sensor value when the command "ipmitool sel elist" is executed

[Tony Lee (李文富)]

> On 10/27/19 11:41 PM, Tony Lee (李文富) wrote:
> > Hi Jason,
> >
> > We know that when we execute the command "ipmitool sel elist", it will
> return something like the following,
> > "18 | 10/16/19 | 18:28:41 UTC | Temperature nvme0 | Upper Non-critical
> going high | Asserted | Reading 72 > Threshold 70 degrees C".
> >
> > I met a problem that when the sensor value in the d-bus is negative, the
> current reading in "ipmitool sel elist" will be 0.
> > It seems that because the type of scaledValue is defined "uint32_t", there is
> always a none negative value even current value is a negative value obtained
> from the d-bus. In
> >
> https://github.com/openbmc/phosphor-sel-logger/blob/master/include/sens
> orutils.hpp#L159
> >
> > Is this is an issue or I need to set it up somewhere?
> 
> If min is < 0, then this should work:
> 
> https://github.com/openbmc/phosphor-sel-logger/blob/6afe9560852c6431c4
> 3c8e79a28e2b7cb498e355/include/sensorutils.hpp#L61
> 
> https://github.com/openbmc/phosphor-dbus-interfaces/blob/12162be363f11
> b9dafa92b5379db671712b3523c/xyz/openbmc_project/Sensor/Value.interfac
> e.yaml#L28
> 
> It uses MinValue < 0 to determine if the sensor is signed or not.

Hi James,

Yes, My MinValue and min are < 0.
I understand that If min is < 0 then bSigned = true finally it will return static_cast<int8_t>(scaledValue)
then this should work. But, after 
https://github.com/openbmc/phosphor-sel-logger/blob/6afe9560852c6431c43c8e79a28e2b7cb498e355/include/sensorutils.hpp#L159
I got scaledValue = 0 and return 0 in the end.

There are another question that why is "scaledValue" defined as uint32_t?
Shouldn't it return a byte(uint8_t) after calculation?

Here is my settings and debug logs:
max = 127.000000
min = -128.000000
value = -1.000000
mValue = 1
rExp = 0
bValue = 0
bExp = 0
bSigned = true
scaledValue = 0

Thanks,
-Tony

> Thanks,
> 
> -James
> 
> >
> > Thanks
> > Best Regards,
> > Tony
> >