> On Mar 8, 2019, at 9:40 AM, Eric Auer <[email protected]> wrote:
> 
> 
> Hi Louis,
> 
>> Do you mean something like the SHSU* Image/ISO to RAMDrive utils [0][1][2]
>> when you said, " If we had a driver that could directly use  CD/DVD media
>> like a hard drive and cache changes to RAM, then things could be different
>> and possibly even better"?
> 
> The problem is the CACHE CHANGES TO RAM part in the above. The drivers
> (shsufdrv, shsucdx) only allow read-only access to CD / DVD as actual
> drives or as ISO disk images stored on another local drive.

Yep :-)

> 
> Examples for what Linux would use for CD/DVD boots with RAM writes:
> 
> https://en.wikipedia.org/wiki/OverlayFS
> 
> https://en.wikipedia.org/wiki/UnionFS
> 
> https://en.wikipedia.org/wiki/Aufs
> 
> This can be combined with compressed read-only systems such as SquashFS
> or CramFS. As DOS barely supports any overlay stuff, another question
> would be which FreeDOS packages work directly from read-only media. My
> guess is: MOST will!

I agree that most of BASE (and many more packages) could run without issue on a 
read-only filesystem. Also with a TEMP dir living on a RAM drive, you could 
even use I/O redirection (type blahblah.txt | more).  For many utilities, a 
writable filesystem is irrelevant. But for any program that has settings the 
user may wish to change or updates files (like game scores), it could be a 
problem. Most programs were not designed to run read-only. 
> 
> That means that the RAMDISK and RAM requirements for a FreeDOS live CD
> can be a lot smaller, because most packages can be used from their pre-
> installed instance which can be part of a normal CD / DVD.
> 
> Only a few would have to be unpacked to a ramdisk when booting in live
> CD mode before they can be used. Even that could be tweaked, for example
> by asking the user which 1 of the 3 largest packages among those which
> need to be on writeable disk should be installed into the ramdisk.

I considered this. However, running the entire OS in RAM has some advantages. 
For instance in a single CD/DVD system, you could swap the disc and install/run 
programs or games not provided on the FreeDOS release media.  

> 
> It would be interesting to see some stats about how much disk space
> FreeDOS 1.3 RC1 needs worst case on harddisk (possibly with 32kB per
> cluster, too) and how much of that needs to be on writeable media
> when considering a live CD. I hope the experts can extract this from
> their package list and database. Thanks :-)

This is just information for RC1. Not disk space requirements…

Total packages:                 298
All packages (compressed)       532 MB
All packages (uncompressed) 1.1 GB (30,806 files, some source trees contain 
LFNs and remain compressed)
All packlages (uncompressed binaries)  682 MB + 227 MB (compressed sources) = 
909 MB (17,653 files + 1 massive source zip)

:-)

Jerome



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