[uml-devel] [PATCH] um: Print minimum physical memory requirement

[uml-devel] [PATCH] um: Print minimum physical memory requirement

[Thomas Meyer]

Print a more sensible message about the minimum physical memory
requirement.

Signed-off-by: Thomas Meyer <thomas@m3y3r.de>
---
diff --git a/arch/um/kernel/physmem.c b/arch/um/kernel/physmem.c
index 549ecf3..a91cf05 100644
--- a/arch/um/kernel/physmem.c
+++ b/arch/um/kernel/physmem.c
@@ -63,16 +63,23 @@ void __init setup_physmem(unsigned long start, unsigned long reserve_end,
 	unsigned long reserve = reserve_end - start;
 	int pfn = PFN_UP(__pa(reserve_end));
 	int delta = (len - reserve) >> PAGE_SHIFT;
-	int err, offset, bootmap_size;
+	int err, offset, bootmap_size, map_size;
+
+	offset = uml_reserved - uml_physmem;
+	map_size = len - offset;
+	if(map_size <= 0) {
+		printf("Too few physical memory! Needed=%d, given=%d\n",
+		       offset, len);
+		exit(1);
+	}
 
 	physmem_fd = create_mem_file(len + highmem);
 
-	offset = uml_reserved - uml_physmem;
 	err = os_map_memory((void *) uml_reserved, physmem_fd, offset,
-			    len - offset, 1, 1, 1);
+			    map_size, 1, 1, 1);
 	if (err < 0) {
 		printf("setup_physmem - mapping %ld bytes of memory at 0x%p "
-		       "failed - errno = %d\n", len - offset,
+		       "failed - errno = %d\n", map_size,
 		       (void *) uml_reserved, err);
 		exit(1);
 	}



------------------------------------------------------------------------------
Dive into the World of Parallel Programming The Go Parallel Website, sponsored
by Intel and developed in partnership with Slashdot Media, is your hub for all
things parallel software development, from weekly thought leadership blogs to
news, videos, case studies, tutorials and more. Take a look and join the 
conversation now. http://goparallel.sourceforge.net/
_______________________________________________
User-mode-linux-devel mailing list
User-mode-linux-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel

Re: [uml-devel] [PATCH] um: Print minimum physical memory requirement

[Geert Uytterhoeven]

On Sat, Mar 28, 2015 at 10:49 AM, Thomas Meyer <thomas@m3y3r.de> wrote:
>
> Print a more sensible message about the minimum physical memory
> requirement.
>
> Signed-off-by: Thomas Meyer <thomas@m3y3r.de>
> ---
> diff --git a/arch/um/kernel/physmem.c b/arch/um/kernel/physmem.c
> index 549ecf3..a91cf05 100644
> --- a/arch/um/kernel/physmem.c
> +++ b/arch/um/kernel/physmem.c
> @@ -63,16 +63,23 @@ void __init setup_physmem(unsigned long start, unsigned long reserve_end,
>         unsigned long reserve = reserve_end - start;
>         int pfn = PFN_UP(__pa(reserve_end));
>         int delta = (len - reserve) >> PAGE_SHIFT;
> -       int err, offset, bootmap_size;
> +       int err, offset, bootmap_size, map_size;

I think all "int" variables in this function (except for "err") should be
"unsigned long", to avoid overflows on 64-bit systems.

> +       offset = uml_reserved - uml_physmem;
> +       map_size = len - offset;
> +       if(map_size <= 0) {
> +               printf("Too few physical memory! Needed=%d, given=%d\n",
> +                      offset, len);
> +               exit(1);
> +       }
>
>         physmem_fd = create_mem_file(len + highmem);
>
> -       offset = uml_reserved - uml_physmem;
>         err = os_map_memory((void *) uml_reserved, physmem_fd, offset,
> -                           len - offset, 1, 1, 1);
> +                           map_size, 1, 1, 1);
>         if (err < 0) {
>                 printf("setup_physmem - mapping %ld bytes of memory at 0x%p "
> -                      "failed - errno = %d\n", len - offset,
> +                      "failed - errno = %d\n", map_size,
>                        (void *) uml_reserved, err);
>                 exit(1);
>         }

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds