On 5/20/13 6:48 AM, John Baldwin wrote:
On Thursday, May 16, 2013 2:41:27 am Konstantin Belousov wrote:
The ddb use of hardware watchpoints on the x86 architectures is known to
be lacking. There are at least two known problems. One is the improper
interaction with the user-mode debuggers which use debug registers.
Another is that ddb only loads the debug registers for the watchpoint
into the CPU which is executing ddb code, not setting up non-current
processors.
Not touching the first problem for now, I want to fix the second issue,
since as is, hardware watchpoints are useless on SMP. Patch below makes
the stopped processors to load the debug registers after resuming from
the stop handler, if directed by ddb.
Also the patch contains two other commands for ddb which made my
exprerience with debugger on amd64 better. The 'show pginfo[/p] addr'
command dumps the vm_page_t information, either by vm_page address, or,
if the /p modifier is specified, by the physical page address. The 'show
phys2dmap addr' command translates physical address into the directly
mapped address, which can be accessed from ddb then.
This looks fine to me. It would be nice to fix i386 as well to be consistent.
I would commit the new DDB commands as a separate patch from the watchpoint
fixes.
the big test is to add the support in the gdb stub to use these.. :-)
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