Hello, some questions to the zones. 1) Suppose I have a machine with 512 MB RAM. How is the memory node structured into zones? Is it in this way? ZONE_DMA: 1-16 MB ZONE_NORMAL: 17-512 MB That means, there is no high memory available for those machines with less than 896 MB RAM ? 2) Am I right that access to the kernel in memory is as follows: Virtual Memory --------- + + [kernel linear addresses] + + +-------+ <- 0xC0000000 [PAGE_OFFSET] + + + + + + + + [user-space lin. addresses] + + + + + + --------- <- 0x00000000 Physical Memory --------- + + + + user + + +-------+ + + kernel --------- <- 0x00000000 So, user-space linear addresses are always below 0xC0000000 and if a user-process addresses something beyond this it is somehow prohibited. But in the "real" physical memory, the order is turned around: the kernel resides in the lower regions of the memory and the user-space in the upper regions. Is this correct? 3) Is ZONE_NORMAL used only for the kernel or also for user processes? 4) How much space is reserved for the kernel in the physical memory? 5) I've read something about min_low_pfn, max_low_pfn and max_pfn. So min_low_pfn is the first page frame number after the kernel (after _end). max_low_pfn gives me the last page frame number which is accessible by the kernel directly or in other words: the last page frame number which is used by the kernel for its data structures and so on, max_low_pfn+1 is the first page frame number of a user process. max_pfn is the last page frame number available in the physical address space. I've read this: "In low memory machines, the max_pfn will be the same as the max_low_pfn". In which page frames are the user-level processes then stored? I must have misunderstood something... Thanks Andreas -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
