[webkit-dev] SquirrelFish Extreme for non x-86 platforms
oliver at apple.com
Thu Dec 25 02:54:10 PST 2008
On Dec 25, 2008, at 2:18 AM, Javed Rabbani wrote:
> <"That call to VirtualAlloc is inside a PLATFORM(WIN_OS) guard --
> you should not be hitting it on a non-windows platform">
> You are absolutely right about that. The VirtualAlloc() should never
> be hit on non-Windows platform. Let me clarify, I am not hitting the
> VirtualAlloc call on a non-Windows platform. I was just referring to
> the point that what can be a possible alternative to VirtualAlloc on
> embedded platforms. Looking through the code, the VirtualAlloc is
> enabled for WIN_OS only as expected. For other platforms like
> SYMBIAN for example, the fastMalloc() is enabled with a comment that
> "VirtualAlloc is not available on Symbian, so hack with fastMalloc".
It's perfectly possible it's broken in symbian -- the last symbian
release was from more than two years ago.
A bit of digging showed that Simon Hausmann added the SYMBIAN
fastMalloc branch, which implies this was for WebKit/Qt which builds
with fastMalloc disabled. So that call to fastMalloc is actually just
a call to standard system malloc, which i would guess, just by pure
luck allocates adequately aligned memory.
> What are specific memory requirements that VirtualAlloc() fulfills
> and fastMalloc() does not? What can be the workaround for
> VirtualAlloc() on embedded platforms?
Alignment -- VirtualAlloc, mmap, vm_map all produce page aligned
memory (which is at least 4k aligned), and the posix_memalign version
appears to actually over align memory (my following of the code makes
me thinks it's requesting 64k alignment :-/ )
> I hope my point of concern is clearely stated now.
I'm still not sure what your problem is -- posix systems should
provide mmap or posix_memalign either of which will achieve correct
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