Date: Wed, 01 Dec 2010 21:24:25 -0700 From: Warner Losh <imp@bsdimp.com> To: freebsd-mips@freebsd.org, Alan Cox <alc@cs.rice.edu> Subject: Re: vm_page_startup() Message-ID: <4CF71F79.3020500@bsdimp.com> In-Reply-To: <4CF5E518.20508@rice.edu> References: <4CF5E518.20508@rice.edu>
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On 11/30/2010 23:03, Alan Cox wrote:
> Given this bit of code in the MIPS pmap:
>
> vm_offset_t
> pmap_map(vm_offset_t *virt, vm_offset_t start, vm_offset_t end, int prot)
> {
> vm_offset_t va, sva;
>
> if (MIPS_DIRECT_MAPPABLE(end))
> return (MIPS_PHYS_TO_DIRECT(start));
All mips architectures have at least a small direct map...
> The following in vm_page_startup() can apply to MIPS (as well as amd64):
>
> #ifdef __amd64__
> /*
> * pmap_map on amd64 comes out of the direct-map, not kvm like i386,
> * so the pages must be tracked for a crashdump to include this data.
> * This includes the vm_page_array and the early UMA bootstrap pages.
> */
> for (pa = new_end; pa < phys_avail[biggestone + 1]; pa += PAGE_SIZE)
> dump_add_page(pa);
> #endif
>
> Even if a particular MIPS-based machine didn't wind up using the
> direct map for the pmap_map calls in vm_page_startup() there would be
> no harm in having called dump_add_page(). On the other hand, if you
> don't call dump_add_page() when the direct map is used, you're crash
> dump will be missing some kernel data structures.
So would you suggest having:
#if defined(__mips__) || defined(__amd64__)
or
#if __VM_HAS_DIRECT_MAP
and adding that define to pmap.h for mips and amd64? I'm leaning to the
latter, since I don't like #ifdef arch in vm/* code on general
principles, but you're the maintainer...
Warner
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