Date: Mon, 20 May 2013 09:48:46 -0400 From: John Baldwin <jhb@freebsd.org> To: freebsd-amd64@freebsd.org Cc: Konstantin Belousov <kostikbel@gmail.com>, amd64@freebsd.org, current@freebsd.org Subject: Re: Fix amd64 ddb hardware watchpoints for SMP Message-ID: <201305200948.46211.jhb@freebsd.org> In-Reply-To: <20130516064127.GC3047@kib.kiev.ua> References: <20130516064127.GC3047@kib.kiev.ua>
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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. -- John Baldwin
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