On Fri, Dec 14, 2007 at 09:31:27AM -0800, John Reiser wrote:
> In arch/um/kernel/mem.c, mem_init calls map_cb twice:
> once directly and once indirectly via initial_thread_cb. Why?
>
> -----
> void mem_init(void)
> {
> /* clear the zero-page */
> memset((void *) empty_zero_page, 0, PAGE_SIZE);
>
> /* Map in the area just after the brk now that kmalloc is about
> * to be turned on.
> */
> brk_end = (unsigned long) UML_ROUND_UP(sbrk(0));
> map_cb(NULL);
> initial_thread_cb(map_cb, NULL);
> -----
It's a bug. That's left over from the tt mode days, when the kernel
ran in the same address spaces as its processes and there was a
separate thread ptracing everything. The tracing thread address space
needed to be kept in sync with the others, and this was one part of
that.
Jeff
--
Work email - jdike at linux dot intel dot com
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