[Simh] Way out idea for simh

[Johnny Billquist]

On 2016-04-20 19:19, Jonathan Willams wrote:
>> On Apr 20, 2016, at 1:04 PM, Johnny Billquist <bqt at softjar.se> wrote:
>>
>> On 2016-04-20 18:58, Jonathan Willams wrote:
>>> I think a more useful solution would be to engineer FUSE filesystems for
>>> various file system formats. It removes the necessity to modify simh or
>>> the guest OS.
>>
>> Except you need to modify every host OS to add a userland bridge from the kernel to userspace in the file subsystem, in order to then implement the file system in userland.
>> Not to mention that not all systems easily even allows such a construct.
>
> Yeah, I’m not suggesting that we port FUSE to RT-11 or VMS :)

Ok. So FUSE on the host side then, and implementing every file system 
you might see on the emulated side, which might have very different 
properties to what the host is able to understand.
Things like file attribute metadata in Files-11, or bytes that can be 
between 1 and 36 bits in TOPS-20...

>> Or are you suggesting that you would implement (in Linux or whatever) a userland implementation for each file system you might have on every simulated system? That can also become very interesting, as some file systems have properties that Unix do not have, so exposing this in Unix would be rather magic. Not to mention complex.
>
> The original post was about "how to get files copied between the host and the emulated machines”. The notion of multiple records/streams/forks in guest OSes having not equivalent representation isn’t fixed by FTP either. Is the expected use case to transfer archive files the guest and host? I’m guessing most archive formats have a linear representation like tar?

Right. When it comes to binary data, you are mostly screwed, unless you 
know very well what you are doing, and how.
So we're down to text files. But text files are also dealt with very 
differently on different systems. However, FTP as well as Kermit, do 
provide a universal format for text, and each side then transforms it to 
the correct local storage as a part of the transfer, so you can actually 
expect this to work right.

As far as archive formats go, it very much differs from system to system 
if you have something like that, and with a linear format even close to 
what tar looks like.
So don't expect too much...

   Johnny