Dear all, For research purposes I need some userspace memory pages to be in uncacheable mode. I am using two different Intel architectures (Sandy Bridge and Haswell) and two different kernels (2.6.32-358 and 3.19.0-28). The non-temporal stores from Intel assembly are not a valid solution so I am programming a kernel module that gets a set of pages from user space reserved with posix_memalign (get_user_pages) and then sets them as uncacheable (I have tried set_pages_uc and set_pages_array_uc). When I use one page, the access times are not very coherent and with more than one page the module crashes (in both architectures and both kernels). I wonder if I am using the correct approach or if I have to use kernel space pages in order to work with uncacheable memory. Or if I have to remap the memory. Just in case it makes it clearer, I am attaching the relevant lines of a kernel module function that should set the pages as uncacheable. (This function is the .write of a misc device; count is treated as the number of pages). Best and Thanks, Sabela. struct page *pages; //defined outside in order to be able to set them to WB in the release function. int numpages; static ssize_t setup_memory(struct file *filp, const char __user *buf, size_t count, loff_t * ppos) { int res; struct vm_area_struct *vmas; numpages = count/4096; down_read(¤t->mm->mmap_sem); res = get_user_pages(current, current->mm, (unsigned long) buf, numpages, /* Number of pages */ 0, /* Do want to write into it */ 1, /* do force */ &pages, &vmas); up_read(¤t->mm->mmap_sem); numpages=res; if (res > 0) { set_pages_uc(pages, numpages); /* Uncached */ printk("Write: %d pages set as uncacheable\n",numpages); } else{ pr_err("Couldn't get pages to set them as UC :(\n"); return -EAGAIN; } }