I want to (early in system initialization) exclude some contiguous physical memory from one or more memory banks so that it won't be mapped in the normal kernel 1-to-1 mapping (so that it can be mapped uncached, strongly ordered, etc. as needed -- I know that it is forbidden to have a cached and an uncached mapping to the same memory) and so that it won't be freed into the kernel memory allocator (so that it won't fragment and can be allocated using genalloc). I have tried to find a clean way to do this, but none of the approaches I've considered seem very good: 1. Add a hook to the memory tag parsing routine to (possibly) change each tag before arm_add_memory() is called, or alter arm_add_memory() itself. 2. Add a hook at the beginning of paging_init() to inspect and alter the meminfo memory bank starts and sizes as needed. 3. Wait until after the memory is added to the normal kernel memory pool and somehow get it back out (I can't use alloc_bootmem() or related functionality of course since then the memory will be part of the cached kernel 1-to-1 1M page mapping, precluding use of ioremap() on it). A further drawback for #1 is that I'd really like to see all of the available memory banks before deciding which memory to steal (we often have multiple memory banks on our platforms). Perhaps there is a solution for this problem that already exists that I'm unaware of (or at least community consensus about how one should add this functionality). I believe Russell King has stated that he intends to carve out memory that can be used for dma_alloc_coherent(), that won't be mapped otherwise by the kernel. I'd like to know how he is planning to do this, as I could hopefully do something similar. Thanks. Larry Bassel -- Sent by an employee of the Qualcomm Innovation Center, Inc. The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum. -- To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
