Re: [Boost-users] Memory mapped files

Subject: Re: [Boost-users] Memory mapped files
From: Simon Giddings (simon.giddings_at_[hidden])
Date: 2019-01-23 08:15:49

Sorry, but this is a very specific Boost question as we are using the 
Boost memory mapping system.

So, if I understand correctly, you are saying that Boost does / cannot 
garantee compatibility between OS and cpu architecture ?
This would mean that Boost leverages heavily the underlying OS services 
where available.
Having said that, other than doing a "memory dump", is it possible to 
get Boost to serialise the data out to disk ?

On 23/01/2019 02:33, Niall Douglas via Boost-users wrote:
>> We are developing a system which heavily uses memory mapped files.
>> These files are initially created under a unix system, but will then be
>> used in portable systems such as Android and iOS.
>> We are having some problems loading memory mapped files created under
>> Unix into Android.
>>
>> Is this scenario even possible ?
>> Are the memory mapped files compatible between systems ?
> This kind of question has nothing to do with Boost, and would be better
> asked on Stackoverflow.
>
> However yes Android supports memory mapped files just fine. Free address
> space is very limited though, so what works on 64 bit workstations may
> not work on 32 bit Android. Also, Intel CPUs are not ARM CPUs, padding
> of structs will be different, floating point numbers may have a
> different representation or be interpreted a bit differently, there are
> a few other differences.
>
> With discipline memory mapped files usable on both architectures can be
> devised, but usually with a performance penalty on all platforms. In the
> end there is no free lunch.
>
> Niall
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