Messages in this thread | | | Subject | virt_to_bus and >1G of memory (was MAX_DMA_ADDRESS ...) | Date | Wed, 11 Nov 1998 19:58:36 +0100 | From | Jan Kasprzak <> |
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In my previous mail I wrote: : And another question related to the virt_to_bus on x86: : This function is defined as (x) & ~PAGE_OFFSET. It works for the current : value of the PAGE_OFFSET, but IMHO it does not work when I change the : PAGE_OFFSET to 0x70000000, as suggested in <asm-i386/page.h> for >1GB RAM : machines. Shouldn't the virt_to_bus be defined as (x)-PAGE_OFFSET ? : The physical memory is mapped 1:1 from the PAGE_OFFSET virtual address, IIRC.
Can anybody explain this to me? Is (x)-PAGE_OFFSET at any chance slower or less efficient than (x)&~PAGE_OFFSET?
-Yenya
-- \ Jan "Yenya" Kasprzak <kas at fi.muni.cz> http://www.fi.muni.cz/~kas/ \\ PGP: finger kas at aisa.fi.muni.cz 0D99A7FB206605D7 8B35FCDE05B18A5E // \\\ Czech Linux Homepage: http://www.linux.cz/ /// /// I think I'd rather be forced to learn perl than 68020 MMU. -Alan Cox \\\
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