Re: Nuwa on desktop

[Jim Porter]

On 04/07/2015 06:06 PM, Robert O'Callahan wrote:
> On Wed, Apr 8, 2015 at 8:00 AM,  wrote:
>> Not sure do what degree we can replicate on Windows what we do on 
>> FFOS to launch content processes.
> 
> The Cygwin people have looked into fork() in Windows a bit. Some 
> links: 
> http://www.cygwin.com/ml/cygwin-developers/2011-04/msg00036.html 
> https://github.com/kaniini/win32-fork/blob/master/fork.c It doesn't 
> look promising. Maybe if would work if we ever get to the point
> where a content process doesn't need to use any Win32 APIs.

Even if you used something like Cygwin's fork(), it wouldn't help you,
since their implementation isn't copy-on-write:

  "Currently, the Cygwin fork is a non-copy-on-write implementation
  similar to what was present in early flavors of UNIX."[1]

As far as I know, it's flat-out *impossible* to implement copy-on-write
process creation using the Win32 API (and if it's not actually
impossible, it's pretty close). The NT API is another story, but unless
you want to use Windows Services for UNIX / Interix, you're probably not
going to get access to the NT kernel features you'd need to do it.

> We might be able to do something Nuwa-like where Gecko subsystems
> use an explicit shared data segment which is a copy-on-write view of
> a file.

I agree. Shared memory (e.g. CreateFileMapping[2]?) seems like the
closest thing on Windows, although that's a part of the Win32 API I've
never touched.

- Jim

[1] http://www.cygwin.com/cygwin-ug-net/highlights.html
[2]
https://msdn.microsoft.com/en-us/library/windows/desktop/aa366539%28v=vs.85%29.aspx
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Nuwa on desktop

[Robert O'Callahan]

On Wed, Apr 8, 2015 at 8:00 AM,  wrote:

> Not sure do what degree we can replicate on Windows what we do on FFOS to
> launch content processes.


The Cygwin people have looked into fork() in Windows a bit. Some links:
http://www.cygwin.com/ml/cygwin-developers/2011-04/msg00036.html
https://github.com/kaniini/win32-fork/blob/master/fork.c
It doesn't look promising. Maybe if would work if we ever get to the point
where a content process doesn't need to use any Win32 APIs.

We might be able to do something Nuwa-like where Gecko subsystems use an
explicit shared data segment which is a copy-on-write view of a file.

Rob
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