Messages in this thread | | | Subject | Re: ACPI fundamental locking problems | Date | Tue, 3 Jul 2001 22:37:14 +0100 (BST) | From | Alan Cox <> |
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> This goes to the special nature of the Global Lock. If we cannot acquire it, > we set a bit, and the system interrupts when it is released. Please see > acpi_ev_acquire_global_lock().
Gotcha..now I follow - I read it as acquire or spin not acquire or fail
> > if you make a callback from the ACPI code - eg power > > management that itself > > needs to call AML code ? > > All we do at interrupt level is signal the semaphore that threads needing > the GL have blocked on. They continue execution at non-interrupt level.
Obvious question - you call kmalloc with that lock held - that can sleep as it is GFP_KERNEL so other threads can run and make acpi calls .. I assume the other threads block on the acpi lock, and the kmalloc eventually returns.
> > Microsoft very early on in debugging Win2K problems ask > > people to use non > > ACPI settings. > > What is your source for this? They certainly could have said that, but > everything I've heard is that MS was so committed to ACPI, they almost left > APM support out of W2K.
Microsoft helpdesk engineers I know (contrary to assumptions from some quarters there is a lot of respect between some of the MS and linux folks for each others work)
> 3) ACPI increases visibility of vendor code. You can disassemble AML. You > can step through it with our debugger.
Well actually the license on the intel bios says not. Of course the license is invalid here but nevertheless..
> > Governments. They'd hate the US to get prior warning of say protestors > > walking into their top secret menwith hill base playing the > > mission impossible > > theme tune then chaining themselves to things.. > > You're kidding.........right?
No. There are people more paranoid than I care to consider sane. They have lots of money. There are also a bunch of greenpeace people who today walked straight into a US top secret base in the UK singing the mission impossible theme tune .. which did you doubt ?
[Come to think of it which do you find the more improbable ..]
Alan
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