bug#74805: 30.0.92; Trying to build scratch/igc on Cygwin

[Ken Brown <kbrown@cornell.edu>]

On 12/22/2024 3:32 AM, Richard Brooksby wrote:
> On 2024-12-22 08:24, Richard Brooksby wrote:
>> On 2024-12-21 16:56, Ken Brown wrote:
>>> On 12/21/2024 2:24 AM, Eli Zaretskii wrote:
>>>>> Date: Fri, 20 Dec 2024 18:48:37 -0500
>>>>> Cc: 74805@debbugs.gnu.org, Richard Brooksby <rb@ravenbrook.com>
>>>>> From: Ken Brown <kbrown@cornell.edu>
>>>>> 3. The "mmap" branch is a straightforward port, mostly imitating the
>>>>> FreeBSD port.  It currently (with Cygwin 3.5.5) fails because of a
>>>>> limitation of Cygwin's mmap.  But I have a simple patch to Cygwin 
>>>>> in the
>>>>> works that removes that limitation.  With that patch, 37 of the 38 MPS
>>>>> tests pass.  I still need to debug the failing test.  I'm cautiously
>>>>> optimistic that I can get this approach to work.  Either way, I expect
>>>>> the Cygwin patch to soon be available in a test release of Cygwin 
>>>>> 3.6.0
>>>>> so that other Cygwin users can try it.
>>>>
>>>> Thanks for the update, I think this is very good news.
>>>
>>> I could use some help from the MPS experts in debugging the failing 
>>> test, which is arenacv.  I ran the test under strace and didn't see 
>>> any mmap or munmap failures.  I'm attaching the test log, which 
>>> doesn't mean a thing to me.  I also built an unoptimized arenacv and 
>>> can run it under gdb if someone tells me what to look for.
>>
>> Hello.  I can't offer much direct help just now, but here's where I'd 
>> start.
> ...
>  > It's very unlikely that you're actually running out of address space 
> on a 64-bit system.
> 
> I should add that arenacv is a coverage test that is *trying* to provoke 
> the ResRESOURCE error paths in some circumstances https://github.com/ 
> Ravenbrook/mps/blob/9fd0577cf1231e61c9801c81499e5d16d0743806/code/ 
> arenacv.c#L461 but note that this isn't where the test is failing.  
> However, it may be relevant, perhaps if your munmap doesn't successfully 
> free address space.
Thanks!  You've given me some good hints.

Ken