On Wed, Feb 14, 2007 at 10:06:53AM +0900, Roman Mashak wrote: > Hello, Erik! > You wrote to "Roman Mashak" <mrv@xxxxxxxxxxxxx> on Tue, 13 Feb 2007 > 13:13:33 +0100: > > [skip] > ??>> ...)' call. By the time of this call 'tx_buf' has been properly > ??>> initialised and contains addresses of 4 TX descriptors. As I > ??>> understand 'tx_bufs_dma' holds the physical address of DMA memory, > ??>> while 'tx_bufs' - kernel virtual address. What I can't figure out is > ??>> the point of this calculations: tp->tx_bufs_dma + (tp->tx_buf[i] - > ??>> tp->tx_bufs) Why can't we simply have 'tp->tx_bufs_dma + (i * 4)' ? > > EM> Probably because you can't assume that the buffer addresses are 4 bytes > EM> apart. > Why not? Every TX descriptor is of 32 bits length. Then I don't know. Ask on the netdev mailing list, that's where the network developers hang out. Erik -- They're all fools. Don't worry. Darwin may be slow, but he'll eventually get them. -- Matthew Lammers in alt.sysadmin.recovery
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