VirtualAlloc2 Operate Memoryapi.h

From Linix VServer
Jump to navigationJump to search


Reserves, commits, or changes the state of a area of memory inside the virtual handle space of a specified process (allotted memory is initialized to zero). The handle to a process. The function allocates memory inside the digital tackle house of this process. OPERATION entry right. For extra info, see Process Safety and Entry Rights. If Process is NULL, the function allocates memory for the calling process. The pointer that specifies a desired beginning address for the region of pages that you want to allocate. If BaseAddress is NULL, the perform determines the place to allocate the region. Requirements construction must include all zeroes, and the base address should be a multiple of the system allocation granularity. To determine the allocation granularity, use the GetSystemInfo perform. If this deal with is inside an enclave that you have not initialized by calling InitializeEnclave, VirtualAlloc2 allocates a web page of zeros for MemoryWave the enclave at that tackle. The page must be previously uncommitted, and is not going to be measured with the EEXTEND instruction of the Intel Software Guard Extensions programming model.



Address error. That is true for enclaves that do not assist dynamic memory administration (i.e. SGX1). SGX2 enclaves will permit allocation, and the web page should be accepted by the enclave after it has been allocated. The size of the region of memory to allocate, in bytes. The dimensions should all the time be a a number of of the page measurement. Size. This means, for instance, that a 2-byte vary that straddles a web page boundary causes the perform to allocate each pages. The kind of memory allocation. This parameter should contain considered one of the following values. RESERVE and a non-NULL BaseAddress fails until your complete range has already been reserved. An attempt to commit a page that is already dedicated doesn't cause the perform to fail. This implies that you may commit pages without first determining the current commitment state of every page. Other memory allocation capabilities, equivalent to malloc and LocalAlloc, can't use reserved memory until it has been released.



After you exchange a placeholder with a private allocation, to free that allocation again to a placeholder, see the dwFreeType parameter of VirtualFree and VirtualFreeEx. A placeholder is a kind of reserved memory area. A placeholder is a sort of reserved memory area. RESET will include zeros. If you need the range to comprise zeros, decommit the memory and then recommit it. RESET, the VirtualAlloc2 operate ignores the value of fProtect. RESET and the range of memory is mapped to a file. A shared view is simply acceptable if it is mapped to a paging file. This value cannot be used with another value. RESET earlier, the behavior is undefined. RESET, the VirtualAlloc2 operate ignores the value of PageProtection. This parameter also can specify the following values as indicated. The scale and alignment have to be a multiple of the massive-web page minimum. To obtain this worth, use the GetLargePageMinimum perform. A 64K web page is a region of memory that is 64K in measurement, nearly and bodily contiguous, and nearly and bodily aligned on a 64K boundary.



PAGES is pageable, and bodily pages backing the memory are allocated on demand (on the time of entry). PAGES allocation could also be mapped utilizing non-contiguous small pages instead. NONPAGED attribute, the allocation might be mapped utilizing non-paged 64K pages. In that case, if contiguous 64K pages can't be obtained, the allocation will fail. PAGES is specified, the scale and BaseAddress parameters must both be multiples of 64K (BaseAddress could also be NULL). RESERVE and no other values. The memory safety for the area of pages to be allocated. If the pages are being committed, you possibly can specify any one of the memory protection constants. PARAMETER. Each of these extended parameter values can itself have a sort field of either MemExtendedParameterAddressRequirements or MemExtendedParameterNumaNode. If no MemExtendedParameterNumaNode prolonged parameter is offered, then the habits is the same as for the VirtualAlloc/MapViewOfFile functions (that's, the popular NUMA node for the physical pages is set primarily based on the ideal processor of the thread that first accesses the memory).



The number of prolonged parameters pointed to by ExtendedParameters. If the operate succeeds, the return value is the bottom deal with of the allotted area of pages. If the function fails, MemoryWave the return worth is NULL. To get extended error data, name GetLastError. This API offers specialized techniques for managing virtual memory in assist of high-performance games and server functions. For instance, placeholders permit a reserved memory vary to be explicitly partitioned, overlaid, and re-mapped; this can be used to implement arbitrarily extendable regions or virtual memory ring buffers. VirtualAlloc2 additionally permits for allocating memory with a selected memory-alignment. Every page has an related web page state. VirtualAlloc2 can commit pages which are already dedicated, but can't reserve pages which might be already reserved. This implies you'll be able to commit a spread of pages, no matter whether they've already been committed, and the operate won't fail. Normally however, only a minimal range of largely uncommitted pages should be specified, because committing a large number of pages which are already committed can cause the VirtualAlloc2 name to take much longer.