[parisc-linux] Re: CCIO dma io_command and related io_tlb format questions.

[Andrew Gaylard]

Joel Soete wrote:

>>On Tue, Oct 17, 2006 at 11:33:50AM +0200, Joel Soete wrote:
>>    
>>
>>>Any way factorizing (it's well like I would call operation like:
>>>ab+ac = a(b+c)?) PAGE_SHIFT it make the writing lighter imho (at least easiest
>>>to read?):
>>>--- ccio-dma.c.Orig	2006-10-17 10:10:11.000000000 +0200
>>>+++ ccio-dma.c	2006-10-17 10:20:21.000000000 +0200
>>>@@ -1267,16 +1267,15 @@
>>> 	** Hot-Plug/Removal of PCI cards. (aka PCI OLARD).
>>> 	*/
>>>
>>>-	iova_space_size = (u32) (num_physpages / count_parisc_driver(&ccio_driver));
>>>+	unsigned long phys_mem = num_physpages << PAGE_SHIFT;
>>>      
>>>
>>This may be algebraically correct, but I'm concerned about a 32-bit
>>kernel on a machine with 4GB of memory.  That would wrap phys_mem to 0.
>>
>>    
>>
>more reading:
>in this case "Memory truncated" to mem_limit = 3584*1024*1024 (3.5Gb).
>  
>
Funny you should mention this...

Why do we truncate the memory like this?
My 4GB box is now "missing" 512M.

Andrew
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