On Mon, 24 Jan 2000, Alexander Viro wrote:
|>On Sun, 23 Jan 2000, Alan Cox wrote:
|>
|>> > problem. Normal sys_read() and sys_write() would pass copy_to_user() /
|>> > copy_from_user() here. For sys_readv() and sys_writev() - well,
|>> > corresponding function that would copy to/from iovector. IIRC we have
|>> > something like that either in net/core/* or in net/socket.c...
|>>
|>> read and write sometimes lock and DMA from user pages in new driver toys
|>> using Stephen's rawio and kiovec stuff. You would need to be careful how
|>> you arranged it to avoid shooting yourself in the foot on future optimisations
|>
|>Ouch... And what happens if we do write() _not_ from user page? I can't
|>think of a place that would write to character device from kernel space,
|>but...
I want to write raw to a disk device from kernel space for crash dumping,
to avoid potential locks in the page cache.
--Matt
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