Re: [PATCH] long format VHPT

From: Darren Williams <dsw_at_gelato.unsw.edu.au>
Date: 2003-09-27 09:42:02
Hi Arun!

On Fri, 26 Sep 2003, Arun Sharma wrote:

> Darren Williams wrote:
> >+#ifdef CONFIG_IA64_LONG_FORMAT_VHPT
> >+	int cpu = smp_processor_id();
> >+	int i;
> >+	
> >+	if (cpu == 0)
> >+	{
> >+		/* We allocate all VHPTs here as we may not have enough 
> >contiguous memory later */
> >+		/* Also, we cannot use __get_free_pages on the target 
> >processor (until after init_cpu) */
> >+		for (i = 0; i < NR_CPUS; i++){
> >+			vhpt_base[i] = (unsigned 
> >long)__alloc_bootmem(LONG_VHPT_SIZE, LONG_VHPT_SIZE, 
> >__pa(MAX_DMA_ADDRESS));
> >+			printk(KERN_INFO "CPU %d: Long format VHPT 
> >initialised at base address: 0x%lx\n", i, vhpt_base[i]);
> >+		}
> >+	}
> >+#endif
> 
> - Can we avoid allocating VHPTs for non-existent CPUs ?

I should of but this as a bug, that I am working on, currently I set the actual
cpu No. when configuring the kernel this avoids the default of 2-63 CPUs.

> - How about calling alloc_bootmem on cpu0 and __get_free_pages on secondary 
> cpus ?

Will look into this.

> - Does the VHPT size have to be a config option ? Can we not size it based 
> on the size of the physical memory and some user supplied multiplier ?
>

Not sure? 
> I noticed that when we hit ia64_mmu_init() on a secondary processor, cpu0 
> has already made successful calls to __get_free_pages(). But calls from the 
> secondary cpus fail. Does anyone know why ?
> 
> 	-Arun
> 
> PS: patches for some of the above available, but they're based on Matt's 
> earlier patch and need cleaning up.
> 
> -
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--------------------------------------------------
Darren Williams <dsw@gelato.unsw.edu.au>
Gelato@UNSW <www.gelato.unsw.edu.au>
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Received on Fri Sep 26 19:42:26 2003

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