[uml-devel] [PATCH v2] um: Print minimum physical memory requirement

[uml-devel] [PATCH v2] 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..f7af5e6 100644
--- a/arch/um/kernel/physmem.c
+++ b/arch/um/kernel/physmem.c
@@ -61,18 +61,26 @@ void __init setup_physmem(unsigned long start, unsigned long reserve_end,
 			  unsigned long len, unsigned long long highmem)
 {
 	unsigned long reserve = reserve_end - start;
-	int pfn = PFN_UP(__pa(reserve_end));
-	int delta = (len - reserve) >> PAGE_SHIFT;
-	int err, offset, bootmap_size;
+	unsigned long pfn = PFN_UP(__pa(reserve_end));
+	unsigned long delta = (len - reserve) >> PAGE_SHIFT;
+	unsigned long offset, bootmap_size;
+	int err, 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);
 	}



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Re: [uml-devel] [PATCH v2] um: Print minimum physical memory requirement

[Geert Uytterhoeven]

On Fri, Apr 3, 2015 at 1:59 PM, Thomas Meyer <thomas@m3y3r.de> wrote:
> --- a/arch/um/kernel/physmem.c
> +++ b/arch/um/kernel/physmem.c
> @@ -61,18 +61,26 @@ void __init setup_physmem(unsigned long start, unsigned long reserve_end,
>                           unsigned long len, unsigned long long highmem)
>  {
>         unsigned long reserve = reserve_end - start;
> -       int pfn = PFN_UP(__pa(reserve_end));
> -       int delta = (len - reserve) >> PAGE_SHIFT;
> -       int err, offset, bootmap_size;
> +       unsigned long pfn = PFN_UP(__pa(reserve_end));
> +       unsigned long delta = (len - reserve) >> PAGE_SHIFT;
> +       unsigned long offset, bootmap_size;
> +       int err, map_size;

map_size should be unsigned long.

> +
> +       offset = uml_reserved - uml_physmem;
> +       map_size = len - offset;




-- 
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

Re: [uml-devel] [PATCH v2] um: Print minimum physical memory requirement

[Thomas Meyer]

Am Freitag, den 03.04.2015, 15:17 +0200 schrieb Geert Uytterhoeven:
> On Fri, Apr 3, 2015 at 1:59 PM, Thomas Meyer <thomas@m3y3r.de> wrote:
> > --- a/arch/um/kernel/physmem.c
> > +++ b/arch/um/kernel/physmem.c
> > @@ -61,18 +61,26 @@ void __init setup_physmem(unsigned long start, unsigned long reserve_end,
> >                           unsigned long len, unsigned long long highmem)
> >  {
> >         unsigned long reserve = reserve_end - start;
> > -       int pfn = PFN_UP(__pa(reserve_end));
> > -       int delta = (len - reserve) >> PAGE_SHIFT;
> > -       int err, offset, bootmap_size;
> > +       unsigned long pfn = PFN_UP(__pa(reserve_end));
> > +       unsigned long delta = (len - reserve) >> PAGE_SHIFT;
> > +       unsigned long offset, bootmap_size;
> > +       int err, map_size;
> 
> map_size should be unsigned long.

No, this can actually get negative as the memory size needed by the
executable file (linux) can be bigger then the physical memory assigned
to the kernel via "mem=xxx" command line!

> 
> > +
> > +       offset = uml_reserved - uml_physmem;
> > +       map_size = len - offset;
> 
> 
> 
> 

Re: [uml-devel] [PATCH v2] um: Print minimum physical memory requirement

[Geert Uytterhoeven]

On Fri, Apr 3, 2015 at 3:22 PM, Thomas Meyer <thomas@m3y3r.de> wrote:
> Am Freitag, den 03.04.2015, 15:17 +0200 schrieb Geert Uytterhoeven:
>> On Fri, Apr 3, 2015 at 1:59 PM, Thomas Meyer <thomas@m3y3r.de> wrote:
>> > --- a/arch/um/kernel/physmem.c
>> > +++ b/arch/um/kernel/physmem.c
>> > @@ -61,18 +61,26 @@ void __init setup_physmem(unsigned long start, unsigned long reserve_end,
>> >                           unsigned long len, unsigned long long highmem)
>> >  {
>> >         unsigned long reserve = reserve_end - start;
>> > -       int pfn = PFN_UP(__pa(reserve_end));
>> > -       int delta = (len - reserve) >> PAGE_SHIFT;
>> > -       int err, offset, bootmap_size;
>> > +       unsigned long pfn = PFN_UP(__pa(reserve_end));
>> > +       unsigned long delta = (len - reserve) >> PAGE_SHIFT;
>> > +       unsigned long offset, bootmap_size;
>> > +       int err, map_size;
>>
>> map_size should be unsigned long.
>
> No, this can actually get negative as the memory size needed by the
> executable file (linux) can be bigger then the physical memory assigned
> to the kernel via "mem=xxx" command line!

In that case it should be (signed) long.

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