[Vm-dev] Fwd: [Pharo-users] squeak vm without MMU

Bert Freudenberg bert at freudenbergs.de
Thu Jan 13 09:59:34 UTC 2011

Sounds like it could be made to work. Pretty much the only hard requirement is that you need to be able to allocate a big *continuous* chunk of memory (image size + headroom). 

- Bert -

On 13.01.2011, at 08:36, stephane ducasse wrote:

> Begin forwarded message:
>> From: Annick Fron <info at afceurope.com>
>> Date: January 12, 2011 10:26:41 AM GMT+01:00
>> To: A friendly place where any question about pharo is welcome <pharo-users at lists.gforge.inria.fr>
>> Subject: [Pharo-users] squeak vm without MMU
>> Reply-To: A friendly place where any question about pharo is welcome <pharo-users at lists.gforge.inria.fr>
>> Hi,
>> Is it possible to use pharo on a processor with MMU (Memory Unit Management ) ? 
>> Namely my target OS is a Linux with the following differences :
>> ============
>> The kernel is a collection of patches to make the standard Linux kernel run on CPUs that do not have an MMU. As a consequence you will encounter some differences between the kernel and the standard Linux behavior:
>> u no fork() – consider using vfork() instead but beware of the difference of their semantics
>> u no daemon() – it is usually implemented on top of fork and cannot be easily replaced without changing the semantics.
>> u fixed stack size -- the stack of an application is set at execution time and cannot grow during runtime. The default stack size is 4k! It can be increased with the "-s" option of m68k-uClinux-elf2flat.
>> u limited libc compared to glibc -- either add more to libc, or remove some functionality.
>> u no support for ELF binary file format
>> u very limited support for shared libraries due to missing MMU -- all applications get linked statically
>> u mmap() is very inefficient
>> u no paging -- applications have to be loaded completely into RAM, the heap is very susceptible to fragmentation.
>> ========
>> Annick Fron

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