Re: Wiki Edits: adding Richard's comment about mach's memory management issues

[Joshua Branson]

Samuel Thibault <samuel.thibault@gnu.org> writes:

> Hello,
>
> Joshua Branson, le mer. 07 nov. 2018 12:00:48 -0500, a ecrit:
>> -Just like any 32-bit OS without bad tricks, GNU Mach can not cope well with 
>> lots
>> -of memory.  Latest versions of the Debian `gnumach` package will limit 
>> themselves
>> -to around 1.7 GiB of memory. If you want more, you can twiddle the 
>> `VM_MAX_ADDRESS`
>> -limit between kernelland and userland in 
>> `i386/include/mach/i386/vm_param.h`.
>> +The 830MB RAM limit has been removed, but just like any 32-bit OS without 
>> bad tricks,
>> +GNU Mach can not cope well with lots of memory.  Latest versions of the 
>> Debian `gnumach`
>> +package will limit themselves to 3 GiB of memory. If you want more, you can 
>> twiddle
>> +the `VM_MAX_ADDRESS` limit between kernelland and userland in
>> +`i386/include/mach/i386/vm_param.h`, but glibc and the hurd servers will 
>> not cope
>> +well with less than 1 GB.
>
> Mmm, this is outdated. Richard implemented the highmem mapping support
> needed to manage more than 2-3GiB of memory, so we don't have that
> limitation any more. It's however still useful to mention that managing
> a lot of memory with 32bit systems is a bit costly and the 64bit port
> would help on this.

Ok.  I'll see if I can't find that commit message somewhere to find out
more about Richard's highmem mapping support, and perhaps I'll mention
your comment "It's however still useful to mention that managing
a lot of memory with 32bit systems is a bit costly and the 64bit port
would help on this" on that FAQ page.

>
> Samuel