Re: There is no point to specify both MEM_RESERVE and MEM_COMMIT for VirtualAlloc

[Vitaliy Margolen]

Monday, January 2, 2006, 1:23:22 AM, Dmitry Timoshkov wrote:
> Changelog:
>     Dmitry Timoshkov 
>     There is no point to specify both MEM_RESERVE and MEM_COMMIT for
>     VirtualAlloc.

According to MSDN:

"To reserve and commit pages in one step, call VirtualAlloc with
MEM_COMMIT | MEM_RESERVED.
The function fails if you attempt to commit a page that has not been
reserved. The resulting error code is ERROR_INVALID_ADDRESS."

Why do you want to do something that _should_ fail?

Vitaliy Margolen

There is no point to specify both MEM_RESERVE and MEM_COMMITfor VirtualAlloc

[Dmitry Timoshkov]

"Vitaliy Margolen"  wrote:
> According to MSDN:
>
> "To reserve and commit pages in one step, call VirtualAlloc with
> MEM_COMMIT | MEM_RESERVED.
> The function fails if you attempt to commit a page that has not been
> reserved. The resulting error code is ERROR_INVALID_ADDRESS."

You are right. My main objection was that NtAllocateVirtualMemory rounds
passed in base address to a 64k boundary in the MEM_RESERVED case and to
page boundary for MEM_COMMIT one, but since (almost) all the cases in my
patch use NULL as a requested base address that doesn't really matter.