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From: "Mehdi Hashemian" <mhashemian@hotmail.com>
To: linux-kernel@vger.kernel.org
Subject: PTE question
Date: Wed, 18 Sep 2002 18:52:25 -0700
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Hello,

Appreciate if someone checks this piece of code. I try to diable cache and 
write-through bits in PTE but somehow PTE address is within first 16MB of 
memory (DMA_ZONE) and later when Kernel tries to allocate more pages, it 
chooses the same address range and this piece of code corrupts memory by 
ORing these bits. Any help appreciated!

    {
        addr = __get_dma_pages(priority, order);

        int npages = __get_npages(order);
	unsigned long addr2 = addr;
	pgd_t *pgd;
	pmd_t *pmd;
	pte_t *pte;
	int i;

	for (i = 0; i < npages; i++)
	{
	    pgd = pgd_offset(&init_mm, addr2);
	    pmd = pmd_offset(pgd, addr2);
	    pte = pte_offset(pmd, addr2);
	    pte_val(*pte) |= (_PAGE_PCD | _PAGE_PWT);

	    addr2 += PAGE_SIZE;
	}
	__flush_tlb_all();
    }

Mehdi



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