Further discussion of default video quirks

[Danny Kukawka]

On Samstag, 29. November 2008, Matthew Garrett wrote:
> 27d8bdbe7eb0bc5c375b456fc480d6bb235c0dc4 changes the behaviour of the
> build system to explicitly require --enable-video-default-quirks to be
> passed. I think this is a poor choice for several reasons.

That's not correct. If you call ./autogen.sh or ./configure 
without --enable-video-default-quirks it's activated anyway and the file get 
shipped (if the package get generated with make dist*) and installed. The 
parameter is only there to allow distributions/users to install hal-info 
without the file by calling --disable-video-default-quirks.

That's why the rest of the discussion is really unnecessary.

> The problem is that we don't know which quirks a given machine may
> require. The approach taken by the default quirks fdi is to switch on
> most of them. This makes it likely that any necessary quirks are run -
> however, it also makes it possible that one of the quirks will be
> unnecessary and will break resume. However, this doesn't result in any
> increased failure rate. The machine almost certainly failed to resume
> without the quirks - it will also fail to resume with them. While we've
> changed the precise failure mode, we haven't changed the fundamental
> fact that the system doesn't behave usefully. I don't see this as a
> problem.

> The absolute theoretical worst case scenario for having these default
> quirks is that they will break systems that would otherwise resume
> successfully. I am unaware of the existence of any hardware where this
> is true. The more common worst case scenario is where a machine that
> failed to resume continues to fail to resume. The more common case is
> that a machine that previously failed to resume will now work.

As already said in the thread (IIRC): 
- As you already pointed out: This can break machines which may work without 
any quirks. And there are such machines, we have seen such cases in the past, 
where quirks prevented a machine from suspend/resume which worked without any 
quirk.
- This combination isn't really common (I couldn't find any machine with this 
combination in a first looks at the quirk list), it would make more sense (if 
any) to find vendor specific default quirks, since the chance is much better 
to get a working machine.
- It prevents may finding bugs/problems with suspend. Since it may make 
machines working which currently don't work because of e.g. a kernel bug.

> Unless someone has a documented case where this change will break
> otherwise working hardware, I plan to flip the default to install the
> file and allow a compile time argument to disable it. Distributions that
> want their hardware support to be reduced can pass the argument, but
> everyone else gets sensible behaviour out of the box.

Maybe I've overseen something, but this is what hal-info already do. The file 
is part of the package and distributions can disable the installation 
via --disable-video-default-quirks. What's the problem exactly?

Danny