Re: CVS commit: src/sys/arch/mips/mips
On Tue, Nov 09, 2010 at 02:20:11PM -0700, Warner Losh wrote: > >No, it's not obvious from those either, and I'm even familiar with the > >architecture. This whole thing could have been avoided if you'd > >written a clear commit message; can you revise the text in CVS to have > >fewer dangling referents? > > Or better yet, improve the comments so people looking at the code > know what the considerations are? Seems like an area where a > sentence or two would save a lot of grief in the future... *slaps self* done - anyone else who wants to put an oar in please edit accordingly. -- David A. Holland dholl...@netbsd.org
Re: CVS commit: src/sys/arch/mips/mips
On Mon, Nov 08, 2010 at 03:49:09PM -0700, Warner Losh wrote: >>> I don't have a mips1-specific reference on hand, but my recollection >>> is that you need *three* nops when messing with cop0 registers for all >>> effects to flush through. >> locore_mips1.S doesn't agree with your recollection, e.g. mips1_TLBUpdate >> right above mips1_TLBRead. What about it? It has some nops scattered in it, but they're neither documented nor particularly systematic. > mips1 had a 2 stage pipeline, so at most you'd need 1 nop. 3 nops > is for the R4000's and similar. I'm not sure about that. The only docs I still have do not describe the 3-cycle wait for interrupt switching as r4000-specific, although these docs do describe other pipeline hazards as r4000-specific. That doesn't prove much for certain, but it's at least suggestive. (I used to have the Hennessey & Patterson textbook that described the original r2000 in gory detail, but I got rid of it because it was outdated...) Anyway, the exactly one nop that you do see in some mips1 contexts (e.g. branch delays, and using values after fetching them) is the offset between certain pipeline stages, not the total pipeline depth. > Then it got weird with multi-issue, threads, and sometimes silicon > bugs that required more before MIPS32r2 and MIPS64r2 codified a > single, special kind of nop that did the trick. You still need more than one of those in some cases, to the best of my knowledge. -- David A. Holland dholl...@netbsd.org
Re: CVS commit: src/sys/arch/mips/mips
On 11/09/2010 13:54, David Holland wrote: On Tue, Nov 09, 2010 at 01:46:46PM +0200, Antti Kantee wrote: > > Thanks for the extra details. It may be "obvious" with the background > > info you've now provided, but wasn't from your initial commit message. > > Gotta love source-changes-full and nxr.netbsd.org ;) No, it's not obvious from those either, and I'm even familiar with the architecture. This whole thing could have been avoided if you'd written a clear commit message; can you revise the text in CVS to have fewer dangling referents? Or better yet, improve the comments so people looking at the code know what the considerations are? Seems like an area where a sentence or two would save a lot of grief in the future... Warner
Re: CVS commit: src/sys/arch/mips/mips
On Tue, Nov 09, 2010 at 01:46:46PM +0200, Antti Kantee wrote: > > Thanks for the extra details. It may be "obvious" with the background > > info you've now provided, but wasn't from your initial commit message. > > Gotta love source-changes-full and nxr.netbsd.org ;) No, it's not obvious from those either, and I'm even familiar with the architecture. This whole thing could have been avoided if you'd written a clear commit message; can you revise the text in CVS to have fewer dangling referents? -- David A. Holland dholl...@netbsd.org
Re: CVS commit: src/tests/fs/tmpfs
On Tue, 09 Nov 2010, Julio Merino wrote:
> Log Message:
> Remove ugly workaround to skip this if unprivileged-user=_atf and just use
> 'su -m' as pooka@ did in t_mkdir.sh. As he says this may still fail if
> root's shell is csh; we need a better solution.
su -m ${user} -c "/bin/sh -c 'your command here'"
works if you get the quoting right, but I still think you
need a better solution.
--apb (Alan Barrett)
Re: CVS commit: src/tests/fs/tmpfs
On Tue Nov 09 2010 at 13:01:34 +, Julio Merino wrote: > Module Name: src > Committed By: jmmv > Date: Tue Nov 9 13:01:34 UTC 2010 > > Modified Files: > src/tests/fs/tmpfs: t_create.sh > > Log Message: > Remove ugly workaround to skip this if unprivileged-user=_atf and just use > 'su -m' as pooka@ did in t_mkdir.sh. As he says this may still fail if > root's shell is csh; we need a better solution. I suggested a better solution a few weeks ago in email in our unpriv'd discussion. (just in case you missed it in those too long emails)
Re: CVS commit: src/sys/arch/mips/mips
On Tue Nov 09 2010 at 13:10:02 +1100, Simon Burge wrote: > David Holland wrote: > > > On Mon, Nov 08, 2010 at 06:09:39PM +, Antti Kantee wrote: > > > Modified Files: > > > src/sys/arch/mips/mips: locore_mips1.S > > > > > > Log Message: > > > In TLBRead, restore PID before doing the saves so that the caller's > > > TLB entries are used instead of the PID given as the argument. > > > > > > from Alessandro Forin > > > > [ ... ] > > > > Do you have any further explanations or reports of symptoms? I don't > > see anything on any of the mips lists. > > I'm curious about this too. That code hasn't changed for at least > 14 years... Given that it's only called from ddb, i'm not too surprised nobody has noticed. Now, unless someone argues that the stores should definitely happen with the arbitrary PID set up by tlbr, let's flag the change as "obvious", get on with something useful, and leave noppy philosophy to some other book club.
Re: CVS commit: src/sys/arch/mips/mips
On Tue Nov 09 2010 at 22:43:53 +1100, Simon Burge wrote: > > > I'm curious about this too. That code hasn't changed for at least > > > 14 years... > > > > Given that it's only called from ddb, i'm not too surprised nobody has > > noticed. Now, unless someone argues that the stores should definitely > > happen with the arbitrary PID set up by tlbr, let's flag the change as > > "obvious", get on with something useful, and leave noppy philosophy to > > some other book club. > > Thanks for the extra details. It may be "obvious" with the background > info you've now provided, but wasn't from your initial commit message. Gotta love source-changes-full and nxr.netbsd.org ;)
Re: CVS commit: src/sys/arch/mips/mips
Antti Kantee wrote: > On Tue Nov 09 2010 at 13:10:02 +1100, Simon Burge wrote: > > David Holland wrote: > > > > > On Mon, Nov 08, 2010 at 06:09:39PM +, Antti Kantee wrote: > > > > Modified Files: > > > >src/sys/arch/mips/mips: locore_mips1.S > > > > > > > > Log Message: > > > > In TLBRead, restore PID before doing the saves so that the caller's > > > > TLB entries are used instead of the PID given as the argument. > > > > > > > > from Alessandro Forin > > > > > > [ ... ] > > > > > > Do you have any further explanations or reports of symptoms? I don't > > > see anything on any of the mips lists. > > > > I'm curious about this too. That code hasn't changed for at least > > 14 years... > > Given that it's only called from ddb, i'm not too surprised nobody has > noticed. Now, unless someone argues that the stores should definitely > happen with the arbitrary PID set up by tlbr, let's flag the change as > "obvious", get on with something useful, and leave noppy philosophy to > some other book club. Thanks for the extra details. It may be "obvious" with the background info you've now provided, but wasn't from your initial commit message. Cheers, Simon.
