BTW- Keith was 'let go' after IBM dropped Linux support for Thinkpads. There was a /. article on it a little while ago: http://slashdot.org/article.pl?sid=02/06/20/1631257&mode=thread&tid=136 Phil On Fri, Jul 19, 2002 at 10:25:55PM -0400, Mark D. Studebaker wrote: > Attached is a mail from April 2001 on the issue of the sensors-detect > script > from lm_sensors corrupting the eeprom in IBM Thinkpads, which prevents > them from booting. > > As far as I know this conference call never happened. > Nor do I have a record of receiving any response to the questions below. > If any of you at IBM are still involved with Thinkpads we would > like to restart the discussion on how to prevent the corruption. > Please contact us. > > I will forward a second mail just after this one. > > thanks > mds > > > "Mark D. Studebaker" wrote: > > > > Keith, it would be very helpful if you could give us > > the manufacturer and part number of the EEPROM on the PIIX4 bus, > > and anything else that you think may be pertinent or unique to the > > Thinkpad PIIX4 bus (SDA and SCK pullup values, SCK clock speed, ...) > > > > thanks > > mds > > > > Frodo Looijaard wrote: > > > > > > Keith Frechette wrote: > > > > > > > > 1. ThinkPad thermal sensors are not accessible via the PIIX4 chip set. > > > > > > Yes, that much was already clear. That is fine. In a more general case, > > > many things can potentially be attached to the PIIX4 SMBus adapter, > > > ranging from temperature sensors to timer chips. The main problem > > > is to somehow detect what is present. > > > > > > > 2. ACPI is the intended way of accessing the ThinkPad's sensors > > > > > > I am hardly an ACPI expert, so I may be way off here. The problem > > > with ACPI as I have always understood it, is that it is BIOS-based, > > > and that many BIOSes are plain buggy, not SMP safe, not interrupt > > > safe, and generally hard to interface properly with Linux. Note > > > that I am not saying that any of these problems are relevant for > > > Thinkpads (I wouldn't know, as I have never used one), just that > > > they are common for many systems. Also, non-IBM-compatible > > > computers (macs, sparcs etc. etc.) generally don't have anything > > > like the ACPI BIOS, and neither to older IBM-compatible computers. > > > So in the general case, ACPI just does not cut it, and one has to > > > use a lm_sensors-like solution anyway. > > > > > > In the case of the Thinkpads, life is fortunately simple. We > > > can't access the H8 bus directly even if we wanted, due to a lack > > > of documentation; so there is no chance of accidentally accessing > > > the sensor chips directly, thereby triggering one of the > > > nightmare scenarios you mentioned. Therefore, ACPI is the only way > > > to do it (whether the Linux ACPI drivers are already advanced > > > enough is another question entirely, which you would have to take > > > up with the ACPI developers). > > > > > > As I see it, there remain two questions: why does the device that > > > is on the PIIX4 bus get upset so easily disrupting your entire > > > system, and how do we avoid it? I don't know whether you can or > > > are allowed to answer the first question; still, any insight in > > > what is happening under the lid may help us resolve any future > > > problems. If there is any safer way to probe an PIIX4 adapter (or > > > even better, any i2c or SMBus adapter in the more general case), > > > I would dearly want to learn of it. But seeing the history of > > > this bus (as far as I know, it was developed by Philips for embedded > > > systems and appliances), I think it unlikely there is any failsafe > > > method. I could argue that nothing a user does with his machine > > > should have any bearing after a cold reboot and possibly a harddisk > > > restore, at least not without setting a jumper on his mainboard > > > (a common precaution against accidental or malicious reprogramming > > > of your BIOS EEPROM), but that won't help us here. Still, I think > > > it should be of concern to you that a (Windows) virus could easily > > > disrupt the system on purpose in this way. > > > > > > > 3. lm_sensors can be modified to detect "ThinkPads" and to abort gracefully > > > > > > Though I would prefer finding some safe way to scan the PIIX4 bus, > > > I suspect the best we can do is recognize the Thinkpad (perhaps > > > through the PCI id of some always-there-but-never-on-anything-else > > > device?) and simply not allow the PIIX4 driver to attach to it, > > > or something like that (it may be enough to make certain i2c addresses > > > unavailable; that is something that will have to be determined during > > > the call, I think). As you are trying to free this information for > > > public use, I think we should be able to resolve the symptoms of > > > this problem without too much problem. > > > > > > Thanks, > > > Frodo > > > > > > -- > > > Frodo Looijaard <frodol at dds.nl> PGP key and more: http://huizen.dds.nl/~frodol > > > Defenestration n. (formal or joc.): > > > The act of removing Windows from your computer in disgust, usually followed > > > by the installation of Linux or some other Unix-like operating system. -- Philip Edelbrock -- IS Manager -- Edge Design, Corvallis, OR phil at netroedge.com -- http://www.netroedge.com/~phil PGP F16: 01 D2 FD 01 B5 46 F4 F0 3A 8B 9D 7E 14 7F FB 7A
