lkml.org 
[lkml]   [2020]   [Jul]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 1/3] lib: Add a generic copy_oldmem_page()
On Fri, Jul 10, 2020 at 08:55:42PM -0700, Palmer Dabbelt wrote:
> +ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
> + size_t csize, unsigned long offset,
> + int userbuf)
> +{
> + void *vaddr;
> +
> + if (!csize)
> + return 0;
> +
> + vaddr = memremap(__pfn_to_phys(pfn), PAGE_SIZE, MEMREMAP_WB);
> + if (!vaddr)
> + return -ENOMEM;

Doing a memremap for every page is very inefficient. Also I don't see
why you'd want to even do that. All memory is in the direct mapping
for RISC-V. For other architecture that support highmem kmap_atomic_pfn
would do the job, which is what I'd use in a generic version.

\
 
 \ /
  Last update: 2020-07-13 15:08    [W:0.295 / U:1.296 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site