From: Christopher Faylor <cgf-use-the-mailinglist-please@cygwin.com>
To: The Vulgar and Unprofessional Cygwin-Talk List <cygwin-talk@cygwin.com>
Subject: Re: Design mixed 32 and 64 bit systems.
Date: Mon, 02 Dec 2013 21:07:00 -0000 [thread overview]
Message-ID: <20131202210551.GA2497@ednor.casa.cgf.cx> (raw)
In-Reply-To: <529CEDE5.4030703@etr-usa.com>
On Mon, Dec 02, 2013 at 01:30:29PM -0700, Warren Young wrote:
>On 12/2/2013 12:56, Christopher Faylor wrote:
>> On Mon, Dec 02, 2013 at 12:35:00PM -0700, Warren Young wrote:
>>> This happens because POSIX PIDs are in a table that lives in
>>> cygwin1.dll's memory space, and because there are two DLLs, there are
>>> two different PID tables.
>>
>> Actually POSIX pids are Windows PIDs. The distinction becomes fuzzy
>> after an exec, though, where the Cygwin PID continues to be the PID
>> of the process which previously exec'ed it.
>
>Of the four PID values this pair of programs prints, shouldn't at least
>two should be the same, then? I get four different values here:
>
>PARENT: My PID is 5048; created child PID 5684
>CHILD: My PID is 3108; my parent's PID is 1.
The parent pid *is* a cygwin invention (although technically it doesn't
have to be). When executed between different architectures you lose the
parent/child linkage, since as you say, the DLL in the execed process
thinks it's being started from a non-cygwin windows program.
It's a subtle distinction but there is no real table of Cygwin pids
maintained by the DLL. Each process has a shared memory region
associated with it that holds information like the parent pid. This
shared memory region is not recognized between x86/x86_64.
cgf
next prev parent reply other threads:[~2013-12-02 21:07 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-27 20:13 Buchbinder, Barry (NIH/NIAID) [E]
2013-11-27 22:17 ` JonY
2013-11-27 22:27 ` Christopher Faylor
2013-12-02 19:35 ` Warren Young
2013-12-02 19:56 ` Christopher Faylor
2013-12-02 20:30 ` Warren Young
2013-12-02 20:44 ` Warren Young
2013-12-02 21:07 ` Christopher Faylor [this message]
2013-12-17 20:41 ` Christopher Faylor
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