2005-04-08 13:36:24

by Franck Bui-Huu

[permalink] [raw]
Subject: [PATCH] bootmem.c clean up bad pfn convertions

Hi,

As I described in my previous email, bootmem.c does improper
pfn convertions into phys addr. This simple patch fixes that.

Regards,

Franck.



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Attachments:
bootmem.c.patch (2.47 kB)

2005-04-08 23:52:49

by Dave Hansen

[permalink] [raw]
Subject: Re: [PATCH] bootmem.c clean up bad pfn convertions

On Fri, 2005-04-08 at 15:32 +0200, Franck Bui-Huu wrote:
> As I described in my previous email, bootmem.c does improper
> pfn convertions into phys addr. This simple patch fixes that.
...
> - bdata->node_bootmem_map = phys_to_virt(mapstart << PAGE_SHIFT);
> - bdata->node_boot_start = (start << PAGE_SHIFT);
> + bdata->node_bootmem_map = phys_to_virt(pfn_to_phys(mapstart));
> + bdata->node_boot_start = pfn_to_phys(start);

The only arch with phys_to_pfn() defined is UML, so the patch simply
won't compile anything but UML on current kernels (unless I'm missing
something).

Could you try to give us a more complete description of your problem? I
know your memory doesn't start at 0x0, but what problems does that
cause? Does the mem_map[] allocation blow up, etc...

If it's just mem_map[], That calculation could be fixed pretty easily.
Something like

+#ifdef CONFIG_CRAZY_MIPS_FOO_MEM_MAP_START...
+extern unsigned long mem_map_start_pfn
+#else
+#define mem_map_start_pfn 0UL
+#endif
-#define pfn_to_page(pfn) (mem_map + (pfn))
+#define pfn_to_page(pfn) (mem_map + (pfn) - mem_map_start_pfn)

(those names are horrid, please improve them, if you plan to do this)

All of the zone (and allocator) calculations should be just fine,
because it already has a zone_start_pfn.

-- Dave

2005-04-11 08:24:49

by Franck Bui-Huu

[permalink] [raw]
Subject: Re: [PATCH] bootmem.c clean up bad pfn convertions

Dave Hansen wrote:

>The only arch with phys_to_pfn() defined is UML, so the patch simply
>won't compile anything but UML on current kernels (unless I'm missing
>something).
>
>
oops, I forgot to send the part of the patch that defines these macros,
sorry.

>Could you try to give us a more complete description of your problem? I
>know your memory doesn't start at 0x0, but what problems does that
>cause? Does the mem_map[] allocation blow up, etc...
>
>
yes, it actually intends to solve that.

>If it's just mem_map[], That calculation could be fixed pretty easily.
>Something like
>
>+#ifdef CONFIG_CRAZY_MIPS_FOO_MEM_MAP_START...
>+extern unsigned long mem_map_start_pfn
>+#else
>+#define mem_map_start_pfn 0UL
>+#endif
>-#define pfn_to_page(pfn) (mem_map + (pfn))
>+#define pfn_to_page(pfn) (mem_map + (pfn) - mem_map_start_pfn)
>
>
>
>
This is another solution indeed...But you will have to define another
constant which
will be used for virtual to physical address convertion. In my case I have

#define phys_to_pfn(x) (((x) - PHYS_START) >> PAGE_SHIFT)
#define pa(x) ((x) - PAGE_OFFSET + PHYS_START)

and "pfn_to_page" stays untouch.
But I expect your solution easier to implement since as you said
previously no arch
defines "phys_to_pfn".

Thanks

Franck.

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