2007-02-19 22:45:34

by Kumar Gala

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Subject: serial 8250, sysrq, and break

I'm trying to figure out if an issue I'm having with sysrq (more
likely with receiving a BREAK) is a HW issue or software.

If I have a lot of spew in the kernel (like a printk in receive_chars
()) sysrq seems to work properly, in that the character sent after
the break is properly received. However, if I don't have any spew
the character after the break than I get the wrong character:

[ 22.607920] SysRq : in __sysrq_get_key_op key:255
[ 34.856712] SysRq : in __sysrq_get_key_op key:255
[ 44.823519] SysRq : in __sysrq_get_key_op key:252
[ 51.306161] SysRq : in __sysrq_get_key_op key:240
[ 60.947047] SysRq : in __sysrq_get_key_op key:252
[ 65.942674] SysRq : in __sysrq_get_key_op key:128
[ 102.251461] SysRq : in __sysrq_get_key_op key:254

It seems like hw is treating part of the break as a valid received
character. But, wanted to see if there were any ideas before I
consider this a HW issue.

- k