Fwd: PTE question

From: Mehdi Hashemian (mhashemian@hotmail.com)
Date: Fri Sep 20 2002 - 15:09:25 EST


As I did not receive any response for the following question, I appreciate
if someone guide me to the right email list to post this question, if there
is any.

Appreciate it,

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


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;


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