Re: [PATCH] hpwdt: clean up set_memory_x call for 32 bit

[Maxim Uvarov <maxim.uvarov@oracle.com>]

Thomas, will you be able to test patch accoring to  Linus's nr_page note?

Maxim.

On 01/24/2012 01:05 PM, Mingarelli, Thomas wrote:
> Yes I agree that Maxim's patch is correct. The original set_memory_x call for 64 bit was done correctly and the newer calls are wrong.
>
> The 2 pages for the BIOS SD is a known value so it should be safe to use as is.
>
>
>
> Tom
> -----Original Message-----
> From: Wim Van Sebroeck [mailto:wim@iguana.be]
> Sent: Tuesday, January 24, 2012 2:38 PM
> To: Linus Torvalds
> Cc: Maxim Uvarov; linux-kernel@vger.kernel.org; akpm@linux-foundation.org; stable@vger.kernel.org; Mingarelli, Thomas; dann frazier
> Subject: Re: [PATCH] hpwdt: clean up set_memory_x call for 32 bit
>
> Hi Linus,
>
>> So I don't know who is supposed to be handling this (Wim?), but the
>> patch itself looks suspicious.
>
> I asked Tom to look at Maxim's patch and see what it does. Tom was going to look at the patch and
> I'm waiting on feedback from him first. (That's why I din't sent it upstream yet).
>
>> On Sun, Jan 15, 2012 at 8:02 PM, Maxim Uvarov<maxim.uvarov@oracle.com>  wrote:
>>> -       set_memory_x((unsigned long)bios32_entrypoint, (2 * PAGE_SIZE));
>>> +       set_memory_x((unsigned long)bios32_entrypoint&  PAGE_MASK, 2);
>>
>> If it wasn't page-aligned to begin with, then maybe it needs three pages now?
>>
>>> -                               set_memory_x((unsigned long)cru_rom_addr, cru_length);
>>> +                               set_memory_x((unsigned long)cru_rom_addr&  PAGE_MASK, cru_length>>  PAGE_SHIFT);
>>
>> Same here. If we align the start address down, we should fix up the
>> length. And should we not align the number of pages up?
>>
>> In general, a "start/length" conversion to a "page/nr" model needs to be roughly
>>
>>     len += start&  ~PAGE_MASK;
>>     start&= PAGE_MASK;
>>     nr_pages = (len + PAGE_SIZE - 1)>>  PAGE_SHIFT;
>>
>> to do things right. But I don't know where those magic numbers come
>> from. Maybe the "2" is already due to the code possibly traversing a
>> page boundary, and has already been fixed up. Somebody who knows the
>> driver and the requirements should take a look at this.
>
> Valid comments indeed. Tom please take Linus comments with you when you look at the patch.
>
> Dan: I put you in Cc: also so that you can have a look at it also.
>
> Kind regards,
> Wim.
>
>