x86_64 BSP as GSOC2016 project

Tue Mar 1 00:10:44 UTC 2016

On Mon, Feb 29, 2016 at 2:00 PM, Saket Sinha <saket.sinha89 at gmail.com>
wrote:

> On Tue, Mar 1, 2016 at 1:14 AM, Saket Sinha <saket.sinha89 at gmail.com>
> wrote:
> > Hi,
> >
> > Congratulations to the coreboot team for selection in GSOC 2016.
>
> Sorry for the typo. I meant the RTEMS team. I worked for Coreboot last
> year so still relate to  with GSOC everytime mistakenly.
>
> >
> > I am interested in working on x86_64 BSP as GSOC2016 project with
> > RTEMS and with initial guidance from Joel as to how to get started, I
> > am working on the same.
>
>
Great! This is a nice project we need.

Have you done the RTEMS GSoC hello world project?

The x86_64 now has tools for 4.12. It needs a port and a BSP. The BSP can
share
with the pc386 but we likely have to address the dependency on legacy
hardware.
Some of those issues are captured in the pc386 project page. I have started
to try
to fix the dependency on legacy PCI BIOS but there is more like APIC
support and
device probes.

> > Looking forward to working with the community for the same.
> > Regards,
> > Saket Sinha
> >
> >
> > On Wed, Feb 10, 2016 at 7:08 PM, Joel Sherrill <joel at rtems.org> wrote:
> >>
> >> On Feb 9, 2016 10:37 PM, "Saket Sinha" <saket.sinha89 at gmail.com> wrote:
> >>>
> >>> Hi Joel,
> >>>
> >>> Thanks for your inputs.
> >>>
> >>>
> >>>
> >>> On Wed, Feb 10, 2016 at 1:06 AM, Joel Sherrill <joel at rtems.org> wrote:
> >>> >
> >>> >
> >>> > On Tue, Feb 9, 2016 at 12:08 PM, Saket Sinha <
> saket.sinha89 at gmail.com>
> >>> > wrote:
> >>> >>
> >>> >> Hi,
> >>> >>
> >>> >> I think this is early for this but I need to enquire if x86_64_BSP (
> >>> >> https://devel.rtems.org/wiki/Developer/Projects/Open/x86_64_BSP )
> >>> >> could be taken as a GSOC project this year.
> >>> >>
> >>> >
> >>> > Yes. Assuming you mean the x86_64 bit port and accompanying BSP.
> >>> >
> >>> > If you noticed my post yesterday, we have tripped across a new
> embedded
> >>> > PC
> >>> > without legacy PCI BIOS support.
> >>> >
> >>>
> >>> Could you provide the link. I am not able to locate it on mailing list
> >>> or your blog.
> >>
> >> I only posted a question this week had anyone attempted to use RTEMS on
> a PC
> >> without legacy BIOS. I think the answer is no.
> >>
> >> I have done a little searching for how to use the newer UEFI services to
> >> replace those we use the video and PCI but so far have only found high
> level
> >> information.
> >>
> >> Sorry. This one is a known need with only early research. I was going
> to dig
> >> into the FreeBSD source next.
> >>
> >>> > Beyond the obvious port, for the purposes of your effort, there are
> >>> > a couple of bugs and some modernization needed by the pc386 BSP which
> >>> > you will likely have to address.
> >>> >
> >>> > + PCI BIOS uses legacy support. Needs to support new and old for
> 32-bit
> >>> > and new only for 64 bit.
> >>> > + Better APIC support. pc386 uses legacy PIC and some LPIC for SMP.
> >>> > Probably Ok for both 32 and 64 bit to support APIC only.
> >>> > + i386 does not have Thread Local Support. Both should have it.
> >>> > + i386 has a ticket for SMP synchronization during context switch.
> >>> > The code does not use atomics. Should be fixed and x86_64 follow the
> >>> > correct pattern.
> >>> >
> >>>
> >>> So now my question is that could these be solved on an emulator like
> >>> qemu-x86, atleast for an initial POC ?
> >>> I mean is a x86_64 hardware required for it( though I have a Minnowmax
> >>> board.)
> >>>
> >>
> >> I think qemu can be used for all of this. You can certainly do the APIC
> >> support without addressing the legacy video and PCI BIOS.
> >>
> >> Similar for the TLS and SMP issue.
> >>
> >> I believe the entire thing could be brought up and debugged on qemu with
> >> checkouts on real HW. Either the Minnow or even a desktop PC with the
> right
> >> BIOS settings. None of this is particularly new. APIC dates back at
> least a
> >> decade.
> >>
> >>>
> >>> > Basically x86_64 should assume a modern (non-legacy) PC and pc386
> >>> > needs updating to support newer systems. Common hardware platform
> >>> > so hopefully the software is standard.
> >>> >
> >>> > I was going to write this up as a "PC386 Modernization" Project but
> some
> >>> > of it makes sense as a side-effect of your project. That project idea
> >>> > also
> >>> > included killing AT bus NICs which you wouldn't have any reason to
> get
> >>> > near.
> >>> >
> >>> > You need a subtask list (e.g. todo list) and we need to help you
> flesh
> >>> > it
> >>> > out. I only hit a few non-obvious highlights.
> >>> >
> >>>
> >>> Let me know how to dig deeper on this. Looking at the code, right  but
> >>> than exactly what sections ?
> >>>
> >>
> >> libbsp/shared/i386/pci is the current legacy PCI code.
> >>
> >> The IRQ code should also be under shared.
> >>
> >> I will have to feel to see where the video probe that is failing is
> located.
> >>
> >> The nice thing is that each of these three can be completed in the
> context
> >> of the current BSP.
> >>
> >>> Regards,
> >>> Saket Sinha
>
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