Messages in this thread | | | Date | Thu, 28 Oct 1999 22:06:20 +0000 | From | "George T. Talbot" <> | Subject | Does the serial driver (kernel 2.2.12, Intel) still drop characters during heavy IDE disk activity? |
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I've got this touchscreen industrial PC that I'm using that's basically laptop hardware with a touchscreen. It's got 16550A UARTS. The problem I'm having is that I've got a serial device that pumps data into a serial port at 38.4Kbaud, and when the kernel swaps something in or out, more likely than not, the serial driver will lose a character or two.
I searched the archives and found two threads:
"2.2.12 serial driver swapping characters?" (circa Sept. 99)
In this thread started by Ulrich Windl <ulrich.windl@rz.uni-regensburg.de>, there's a discussion about how the serial drivers got weird at 2.2.11+. Sounds a whole lot like what's happening to me.
"pre-patch-2.0.31 try_to_free_page() messages" (circa June 97)
There's a rather fascinating message from Ted T'so discussing an intentional workaround for crappy IDE controllers that causes the serial driver to lose characters. ( http://www.uwsg.indiana.edu/hypermail/linux/kernel/9706.0/0075.html )
Anybody (Ted, maybe) know if the fix described in the June 97 post works with current kernels? Did something else happen to the serial driver? I fear doing what Ted suggests in the post, as he warns of "MASSIVE FILESYSTEM DAMAGE".
I've got a reasonably good test setup here for repeating this problem if anyone's interested. I do not have a reasonable picture of how the serial driver works, however.
Please CC me in replies to this thread, as I can't read fast enough to subscribe to the list.
Thanks.
-- George T. Talbot <george@moberg.com>
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