X-Authentication-Warning: delorie.com: mail set sender to djgpp-bounces using -f Date: Thu, 07 Sep 2006 09:03:52 -0700 From: Ivor Bowden User-Agent: Thunderbird 1.5.0.5 (Windows/20060719) MIME-Version: 1.0 Newsgroups: comp.os.msdos.djgpp Subject: Re: 64 bit access under DOS? References: <44ff387a$0$19628$88260bb3 AT free DOT teranews DOT com> In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Lines: 57 Message-ID: <450035cf$0$19664$88260bb3@free.teranews.com> NNTP-Posting-Date: 07 Sep 2006 15:07:59 GMT X-Complaints-To: abuse AT teranews DOT com To: djgpp AT delorie DOT com DJ-Gateway: from newsgroup comp.os.msdos.djgpp Reply-To: djgpp AT delorie DOT com on 9/7/2006 1:38 AM PDT Rod Pemberton wrote: > > My understanding is that you are wanting a single 64-bit read or write on > the actual hardware data lines, which is/should be a 64-bit data bus. Yes, that's it exactly. > If so, then you'll need to write your own routines using AMD64 (or > equivalent Intel instructions depending on the CPU). I think Intel implemented the AMD64 instruction set, so hopefully I won't need code conditional on the processor, except to test the instructions are valid. > You'll also have to > figure out how to use those instructions either (1) in 32-bit mode (possibly > using instruction overrides?) That would be best. > or (2) by switching into and out of 64-bit > mode without affecting executing 32-bit code such as the DPMI host or > Windows. That sounds difficult. > Also, it should be possible effectively test a 64-bit read/write on a 64-bit > bus by using two 32-bit reads/writes (_farpeekl/_farpokel) to consecutive > addresses. Of course, either (1) half the data lines should be activated > for each read/write and you'd need to monitor two memory/port accesses > instead of one What happens is the data always takes the low path. The 32 bit address determines the destination. I need to test the physical high path. > or (2) the hardware may combine both accesses into a single > 64-bit access (bonus!). That is what I was originally hoping for, but it doesn't happen on my test machine. I'd like to find a solution that has a high probability of working on any given machine. > This is specific knowledge you or the manufacturer > should have or you may be able to determine with your test equipment. > > I really can't help much further. You'll probably need to post to a few > assembly language groups (AMD64 instructions) and a few electrical > engineering groups (test hardware/logic analyzer) for more accurate > answers... For assembly, I'd try alt.lang.asm and comp.lang.asm.x86, but I > haven't seen too many who seem to have much AMD64 knowledge. I don't have > any suggestions for EE groups. Thank you for your advice! > Rod Pemberton Ivor Bowden -- Posted via a free Usenet account from http://www.teranews.com