Messages in this thread |  | | From | Daniel Phillips <> | Subject | Re: [ANNOUNCE] Generalised Kernel Hooks Interface (GKHI) | Date | Mon, 13 Nov 2000 11:30:52 +0100 |
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tytso@mit.edu wrote: > > Date: Fri, 10 Nov 2000 19:29:26 -0800 > From: "Matt D. Robinson" <yakker@alacritech.com> > > We're planning to isolate the write functions as much as possible. > In the past, we've been bitten by this whole concept of Linux "raw I/O". > When I was at SGI, we were able to write to a block device directly > through low-level driver functions that weren't inhibited by any > locking, and that was after shutting down all processors and any > other outstanding interrupts. For Linux, I had given up and stuck > with the raw I/O interpretation of kiobufs, which is just flat out > wrong to do for dumping purposes. Secondly, as Linus said to me a > few weeks ago, he doesn't trust the current disk drivers to be able > to reliably dump when a crash occurs. Don't even ask me to go into > all the reasons kiobufs are wrong for crash dumping. Just read > the code -- it'll be obvious enough. > > Oh, yeah, I could have told you that from the beginning. kiobufs were > never intended to be crash-dump friendly. :-) My preference would be > that each block device that was going to be doing crash dumping would > use a special busy-looping driver that's guaranteed never to fail. > (Sort of like how the serial console driver is done; it's separate from > the rest of the driver, and does not depend on interrupts working.) > Hence my comment about putting that separate bit of code in a page which > is write-protected and segregated from everything else....
This is also needed for single-machine source level kernel debugging.
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