Shady Dell laptop practices

piglet wrote on 1/10/2018 4:28 AM:
> On 10/01/2018 01:24, M Philbrook wrote:
>> In article <p30dle$26q$1@dont-email.me>, erichpwagner@hotmail.com
>> says...
>>>
>>> On 08/01/2018 15:03, bitrex wrote:
>>>> On some of the inexpensive Dell laptops they implement a
>>>> hardware-lockout system intended to prevent you from using aftermarket
>>>> charger bricks to charge the battery. The way they do this is there's a
>>>> chip in the Dell charger that contains a unique identifier which a chip
>>>> on the laptop mobo requests from it on startup over a one-wire interface.
>>>>
>>>> If on boot the BIOS can't confirm that the lockout chip on the mobo has
>>>> asserted the "OEM OK" pin or whatever the BIOS then proceeds to muck
>>>> around with the processor MSRs (model-specific registers) and alter
>>>> their state, specifically the BD_PROCHOT register, which is a flag bit
>>>> that is usually controlled by the motherboard temperature sensor.
>>>>
>>>> Flipping that makes the processor think the motherboard is overheating,
>>>> which disables battery charging and has the additional nice "feature" of
>>>> throttling the processor down to around 400MHz from 2.8 GHz or whatever.
>>>> So not only can you not charge the battery you can't really use the
>>>> laptop on an aftermarket brick even when plugged into the wall. Also
>>>> there's then no way to tell if the laptop mobo is _actually_ overheating
>>>> in that state.
>>>>
>>>> Good news is that the MSRs are accessible via software, so it's not hard
>>>> to write a script that runs after the OS start to flip the bit back, and
>>>> everything is back to normal.
>>>
>>> My Dell laptop charger used a Dallas-Maxim DS2401 serial number 1-wire
>>> device. I didn't know if Dell bought a block of pre-assigned ID numbers
>>> of whether any 1-wire ID would work.
>>>
>>> When the Dell charger died I transplanted the TO-92 sized (easy to
>>> handle) DS2401 from out the original into a kludged splice in the cable
>>> of the replacement charger - which claims to have enough current
>>> capacity. The laptop is happy.
>>>
>>> piglet
>>
>> Why not simply solder the ID chip inside the laptop at the proper pin
>> and then use what ever comes to mind for a supply ?
>>
>
> Two reasons:
>
> 1. It kept the option open of using a genuine Dell charger if one became
> available;
>
> 2. I had not at the time ever opened that laptop and saw no reason to open a
> potential can of worms.

They have worms in Dell notebooks???  Is that to compost the unused bits?

-- 

Rick C

Viewed the eclipse at Wintercrest Farms,
on the centerline of totality since 1998

bloggs.fredbloggs.fred@gmail.com wrote on 1/8/2018 2:03 PM:
> On Monday, January 8, 2018 at 10:04:00 AM UTC-5, bitrex wrote:
>> On some of the inexpensive Dell laptops they implement a
>> hardware-lockout system intended to prevent you from using aftermarket
>> charger bricks to charge the battery. The way they do this is there's a
>> chip in the Dell charger that contains a unique identifier which a chip
>> on the laptop mobo requests from it on startup over a one-wire interface.
>>
>> If on boot the BIOS can't confirm that the lockout chip on the mobo has
>> asserted the "OEM OK" pin or whatever the BIOS then proceeds to muck
>> around with the processor MSRs (model-specific registers) and alter
>> their state, specifically the BD_PROCHOT register, which is a flag bit
>> that is usually controlled by the motherboard temperature sensor.
>>
>> Flipping that makes the processor think the motherboard is overheating,
>> which disables battery charging and has the additional nice "feature" of
>> throttling the processor down to around 400MHz from 2.8 GHz or whatever.
>> So not only can you not charge the battery you can't really use the
>> laptop on an aftermarket brick even when plugged into the wall. Also
>> there's then no way to tell if the laptop mobo is _actually_ overheating
>> in that state.
>>
>> Good news is that the MSRs are accessible via software, so it's not hard
>> to write a script that runs after the OS start to flip the bit back, and
>> everything is back to normal.
>
> They're trying to avoid the bad publicity of a laptop spontaneously combusting because some jerk charged it with a knockoff charger.

It's not a charger, the charger is inside the notebook.  The thing outside 
the laptop is just a power supply.

-- 

Rick C

Viewed the eclipse at Wintercrest Farms,
on the centerline of totality since 1998