Messages in this thread | | | From | "Michael S. Zick" <> | Subject | Re: [Bug Fix]: Do 32-bit table calculations in pre-processor | Date | Fri, 3 Jul 2009 14:41:01 -0500 |
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On Fri July 3 2009, H. Peter Anvin wrote: > Michael S. Zick wrote: > >> > >> The PGTABLE reservation seems much too big. I think 1 page should be > >> sufficient for a system with large pages. Even if not, 0x6d000 is way > >> too large. And they symptoms of failing to reserve the initial > >> pagetable are pretty non-subtle. > >> > > > > Random system halts, deadlocks with interrupts disabled? > > Yup, that sounds familiar. > > > > If I ever get more than a stopped machine with a glowing power light; > > I will be certain to share. > > > > Let's see... on a non-PSE system we may need one PDE and one PTE page > per 4 MB, up to 1 GB, for a total of 256 pages or 1 MB of memory, so in > that sense 0x6d000 (109 pages) doesn't sound at all unreasonable > (non-PSE system with 512 MB of RAM?) > > However, we shouldn't have to do this kind of hacks with > MAPPING_BEYOND_END, and we *certainly* shouldn't do it by implicitly > hard-coding the value of PAGE_SHIFT. >
Good point: (1<<(32-PAGE_SIFT)) would handle other than 4k pages.
I just hardcoded it as a working example of the change from setting the page table size by design rather than numeric error.
And yes, it has 512Mbyte of ram, so 1/2Mbyte page table sounds right to me.
Mike > -hpa >
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