Boost C++ Libraries

No inline-assembler

Some newer compiler (for instance MSVC 10 for x86_64 and itanium) do not support inline assembler. ^[1]. Inlined assembler generates code bloating which his not welcome on embedded systems.

fcontext_t

Boost.Context provides the low level API fcontext_t which is implemented in assembler to provide context swapping operations. fcontext_t is the part to port to new platforms.

	Note
	Context switches do not preserve the signal mask on UNIX systems.

Because the assembler code uses the byte layout of fcontext_t to access its members fcontext_t must be a POD. This requires that fcontext_t has only a default constructor, no visibility keywords (e.g. private, public, protected), no virtual methods and all members and base classes are PODs too.

Protecting the stack

Because the stack's size is fixed -- there is no support for split stacks yet -- it is important to protect against exceeding the stack's bounds. Otherwise, in the best case, overrunning the stack's memory will result in a segmentation fault or access violation and, in the worst case, the application's memory will be overwritten. stack_allocator appends a guard page to the stack to help detect overruns. The guard page consumes no physical memory, but generates a segmentation fault or access violation on access to the virtual memory addresses within it.