From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 19 Apr 2001 22:43:32 +0200 From: Samuel Rydh To: Gabriel Paubert Cc: linuxppc-dev@lists.linuxppc.org Subject: Re: [PATCH] gettimeofday stability Message-ID: <20010419224332.A1021@ibrium.se> References: <20010412010756.A668@ibrium.se> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: ; from paubert@iram.es on Mon, Apr 16, 2001 at 01:25:56PM +0200 Sender: owner-linuxppc-dev@lists.linuxppc.org List-Id: On Mon, Apr 16, 2001 at 01:25:56PM +0200, Gabriel Paubert wrote: > > Ideally, TB should not be touched. Indeed, MOL can run without > > touching TB (but DEC is essential). However, TB needs to be > > modified for 'save session' feature to work. Basically, the RAM > > and cpu state of MacOS is flushed to disk. At a later time, > > MacOS can be restarted instantly. The problem is that MacOS can't > > deal with the TB skip that occurs if the timebase is not restored > > (no big surprise there). > > By touching the TB, you'll also break all other Linux applications which > may have a valid use for the TB. The only noticeable effect is a small clock drift originating from the loading and restoring of the timebase (and of course, only when MOL is running). Whatever MOL puts into TB/DEC is completely invisible to other processes. Anyway, I'll see if I can locate and patch away the use of the timebase register in MacOS - that would allow the save-session feature to work without having to touch the TB. > BTW: how do you handle multiple MOL sessions ? Mutli-session support was actually added a few days ago - a matter of making sure the MOL kernel module keeps session specific data in a single struct, passed as a parameter. > > Anyway, the negative offset check is desirable even if it is > > only the DEC that is touched. > > No, it is not, is is a textbook case of curing the symptom instead of the > cause. Well, what I was looking for was a change to remove the assumption that the timer code was the sole user of the DEC register. Pauls change seems fix that neatly. Regards, /Samuel ---------------------------------------------------------- E-mail WWW: Phone/fax: (home) +46 8 4418431, (work) +46 8 7908470 ---------------------------------------------------------- ** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/