Re: [PATCH 1/4] Add sniffer for Cygwin x86_64 core dumps

Jon Turney
2020-08-22T19:52:41Z

On 22/08/2020 20:41, Simon Marchi wrote:
> On 2020-08-21 12:28 p.m., Jon Turney wrote:
>> On 21/08/2020 17:22, Simon Marchi wrote:
>>> On 2020-08-21 11:25 a.m., Jon Turney wrote:
>>>> The "dumper" currently shipping in x86_64 Cygwin is utterly broken. (See [1] et seq.).
>>>>
>>>> If you use "dumper" from the latest snapshot [2], you may have more success
>>>>
>>>> [1] https://cygwin.com/git/?p=newlib-cygwin.git;a=commitdiff;h=7dd1b08836e8a7bb37d330995096540afce152a0;hp=38f88601469f4a6ab7cf42e1f076775c99eb17f2
>>>> [2] https://cygwin.com/snapshots/
>>>
>>> Ok, thanks for the tip. I'll give it a try with a snapshot.
>>>
>>> Do I just extract cygwin-20200821.tar.xz into my current Cygwin installation to overwrite
>>> the corresponding files? If I want to revert to the stable versions, how can I do that?
>>
>> You should be able to just extract the dumper.exe from that archive, and
>> use it. That's what I would suggest.
>
> Hmm, just tried that, now running "dumper" does nothing:
>
> Baube@DESKTOP-42816MD ~
> $ dumper
>
> Baube@DESKTOP-42816MD ~
> $ echo $?
> 127

Hmmm. This often means the executable can't be started due to problems
loading DLLs.

If you want to pursue this further, running under cygwin's strace (e.g.
'strace dumper') might shed more light.

> One thing that's weird is that in my installation, binaries are in C:\cygwin64\bin,
> whereas in the snapshot, they are in usr/bin. Did the filesystem layout change
> recently?

This is expected.

If you examine the output of 'mount', you'll see that C:\cygwin64\bin is
mounted at /usr/bin