Re: PowerMac G4 booting from memstick image

On 2021-04-19 18:42, Brandon Bergren wrote:
> On Mon, Apr 19, 2021, at 8:05 PM, Mehul Sanghvi wrote:
>> 
>> Thank you for the explanation.  I had seen something regarding SMP on
>> the mailing list back in March
>> and so thought that it might be part of the 13.0 release.
> 
> SMP timebase fixes for G4s are a WIP still currently. I will MFC them to 
> stable/13
> once I have finished them though.
> 
> https://reviews.freebsd.org/D29136
> 
> (IIRC I need to do another rebase because of some recent changes. Will try 
> to get
> back to it soon.)
> 
> I am looking for someone who has a "newer" (i.e. Quicksilver) SMP G4 to 
> assist
> with submitting the platform function so I can analyze it, as I only have an
> ancient Graphite model that uses hardcoded timebase controls.
I think that's what I have. I experienced much the same as the OP is now. So 
got
got frustrated, and gave up.
I'll drag it out again. If I'm right that it's a Quicksilver. I'd be more 
than
happy to help out any way I can. I can't remember. But I think it's a DP 
@800Mgz.

Thanks for all the work you're doing here! :-)

--Chris
> 
> In the meantime, on SMP G4 I recommend continuing to boot with SMP disabled 
> until
> I can get all cases sorted out.
> 
>> 
>> I have made USB flash drive using the 13.0 memstick image, but am
>> unable to boot from there consistently.
> 
> G4s (especially the powerbooks) can be *really* picky about which stick 
> you're
> using. Of the stack of USB sticks that I own, exactly *1* consistently 
> works. I
> started looking into the OpenFirmware ROM to see if I could figure out what 
> is
> going on there, but so far I haven't had any ideas.
> 
> Assuming you have a stick that works, the boot command I generally use (with 
> the
> iso version!) is:
> 
> boot usb1/disk@1:2,\ppc\loader usb1/disk@1:0
> 
>> 
>> The first time, I got to the dialog box asking to choose Live CD, Shell
>> or Install.  I had waited
>> A while to get to that stage, having gone through several minutes of:
>> 
>>    Root mount waiting for: CAM
>> 
>> and also
>> 
>>    aprobe1:ata1:0:1:0 CAM status: Command timeout
>> 
>> 
>> type of messages scrolling by on the screen.
> 
> This may be caused by a descynced timebase. At the loader prompt, do "boot
> kern.smp.disabled=1" (or set it in the loader environment) and see if that 
> fixes
> it.
> 
>> 
>> Having gotten to the point of selecting Install,  the keyboard wouldn’t
>> work.  An Apple keyboard, hooked up via KVM switch, which was working
>> just fine upto that moment.
> 
> I've seen this for some reason on ADB. I can usually work around it by using 
> a USB
> keyboard. But it could be due to screwed up timers (due to timebase desync)
> 
>> I attached the keyboard directly and tried again and now I’ve got the
>> 
>>    mountroot>
>> 
>> prompt as it couldn’t mount /dev/da0s3 the second time around.
> 
> My guess is that the timebase problems caused the controller interrupt 
> threads to
> go comatose or something similar.
>> 
>> 
>> Making a third attempt now, so lets see what happens.  I might look at
>> what Alfredo suggested and write the ISO to the USB stick and see if
>> that works rather than the memstick.img
> 
> Only the iso gets tested. memstick.img is likely going away soon, it doesn't 
> work
> very well and the iso works everywhere.
> 
>> 
>> 
>> Otherwise will just keep running NetBSD till 13.1 comes out.
>> 
>> 
>> cheers,
>> 
>>     mehul
>> 
>> 
>> 
>> > On Apr 19, 2021, at 20:46 , Mark Millard <[email protected]> wrote:
>> >
>> >
>> >
>> > On 2021-Apr-19, at 16:34, Mehul Sanghvi <mehul.sanghvi at gmail.com> wrote:
>> >
>> >> . . .
>> >>
>> >> I’ll go ahead and create an image with 13.0 and see if that works.
>> >
>> > 13.0-RELEASE was a major change, in that 32-bit PowrePC is finally using
>> > modern llvm/clang-based toochain instead of a gcc 4.2.1 based toolchain.
>> > Effectively, pre-13.0 is not as well unsupported at this point, if I
>> > understand right.
> 
> Right.
> 
>> >
>> > In other words, it is unlikely that you would want to use a 12.x
>> > version at all unless you have reasons to be using the old toolchain.
>> >
>> >>  As I understand it 13.0 handles SMP on the G4 better, and since I have a G$ with 2 CPUs, that would be better anyway.
>> >
>> > 13.0-RELEASE does not contain code changes to deal with FreeBSD's
>> > PowerPC problems in that area as far as I know. There is work
>> > going on in/for main in the area but some of it has not been
>> > checked into main yet, if I understand right. The range of 32-bit
>> > PowerMacs covered and if your hardware is (would be) I do not know.
>> >
>> > There are other issues as well. For example:
>> >
>> > Unfortunately, the FreeBSD 32-bit kernel that covers PowerMacs (G3/G4)
>> > slowly zeros out pages of user processes that it should not touch.
>> > This ends up causing some processes to crash and probably other, less
>> > obvious, issues. It is not a reliable environment. To my knowledge,
>> > this area is not under active development currently but the basic
>> > issue of what type of thing is missing was identified some time back.
>> > (The 64-bit kernel that covers G5s does not have this problem.)
> 
> I still haven't been able to reproduce this on G3/G4, but definitely concur 
> that
> there is a page zeroing issue when attempting to use the 32 bit kernel on a 
> G5
> (which has a different MMU -- the kernel interacts with it via bridge mode
> compatibility. I've tried several times to figure out what the heck is going 
> on
> but failed every time.)
> 
> By the way, I *FINALLY* figured out what is going on with moused freaking 
> out. It
> ended up being an oversight in forking that lead to floating point registers
> getting out of sync.
> My current in-testing patch is http://drop.rtk0.net/fork_rework_3.patch -- 
> will be
> submitting it soon once I finish my local testing.
> 
> This issue actually affects ppc64 as well and has probably been the source 
> of some
> mystery crashes when forking.
> 
>> > There is more, but the above two are fairly major items out of the
>> > overall list.
>> >
>> > These issues are not unique to 13.0+ as far as I know. Using 12.x
>> > likely would not avoid them.
> 
> IMO 13 is in better shape than 12.x. I am currently dogfooding it on a G4
> PowerBook on a daily basis and will be continuing to fix issues here and 
> there
> that have been cropping up.
> 
>> >>> On Apr 19, 2021, at 19:10 , Alfredo Dal'Ava Júnior <alfredo at freebsd.org> wrote:
> [snip]
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