[webkit-dev] SquirrelFish Extreme for non x-86 platforms

Maciej Stachowiak mjs at apple.com
Thu Dec 25 15:36:05 PST 2008

On Dec 25, 2008, at 4:51 AM, Oliver Hunt wrote:

> You can manually align the memory, eg.
> char* memory = malloc(size + alignment - 1);
> memory += alignment;
> memory &= ~(alignment - 1)
> return memory;
> The obvious problem with this is that you can't directly free the  
> result as it will not necessarily represent the start of the  
> allocation, but there are mechanisms for working around that  
> (storing the initial allocation address inline in the allocation  
> itself for instance) but there are various trade offs involved.

Doing it this way would also waste memory, specifically it would  
allocate nearly twice the requested size for a block. (It should also  
work on Symbian though).

> --Oliver
> On Dec 25, 2008, at 3:14 AM, Javed Rabbani wrote:
>> Oliver,
>> Thanks a great deal for this explanation. I am considering running  
>> JS SquirrelFish extreme engine on an ARM-based embedded platform.  
>> You are right that posix systems should provide mmap or  
>> posix_memalign that will serve the purpose. I am concerned about  
>> this issue because in my case, there is no mmap, vm_map etc. to do  
>> the job. The only available option is to use standard memory  
>> allocation routines. What is the way out for me to deal with such a  
>> situation? Obviously, standard malloc() call from within  
>> fastMalloc() is not doing anything good for me.
>> Regards,
>> J R Shah

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