[meta-xilinx] [PATCH] machine-xilinx-default.inc: Default to u-boot for Zynq

Thu Apr 27 08:36:13 PDT 2017

> -----Original Message-----
> From: Nathan Rossi [mailto:nathan at nathanrossi.com]
> Sent: Thursday, April 27, 2017 7:11 AM
> To: Manjukumar Harthikote Matha <MANJUKUM at xilinx.com>
> Cc: Philip Balister <philip at balister.org>; meta-xilinx at lists.yoctoproject.org
> Subject: Re: [meta-xilinx] [PATCH] machine-xilinx-default.inc: Default to u-boot for
> Zynq
>
> On 27 April 2017 at 08:21, Manjukumar Harthikote Matha
> <manjukumar.harthikote-matha at xilinx.com> wrote:
> >
> >
> >> -----Original Message-----
> >> From: Philip Balister [mailto:philip at balister.org]
> >> Sent: Wednesday, April 26, 2017 12:38 PM
> >> To: Manjukumar Harthikote Matha <MANJUKUM at xilinx.com>; Nathan Rossi
> >> <nathan at nathanrossi.com>
> >> Cc: meta-xilinx at lists.yoctoproject.org
> >> Subject: Re: [meta-xilinx] [PATCH] machine-xilinx-default.inc: Default to u-boot
> for
> >> Zynq
> >>
> >> On 04/26/2017 03:06 PM, Manjukumar Harthikote Matha wrote:
> >> >
> >> >
> >> >> -----Original Message-----
> >> >> From: Nathan Rossi [mailto:nathan at nathanrossi.com]
> >> >> Sent: Wednesday, April 26, 2017 10:54 AM
> >> >> To: Manjukumar Harthikote Matha <MANJUKUM at xilinx.com>
> >> >> Cc: meta-xilinx at lists.yoctoproject.org
> >> >> Subject: Re: [meta-xilinx] [PATCH] machine-xilinx-default.inc:
> >> >> Default to u-boot for Zynq
> >> >>
> >> >> On 27 April 2017 at 02:41, Manjukumar Harthikote Matha
> >> >> <manjukumar.harthikote- matha at xilinx.com> wrote:
> >> >>>
> >> >>>
> >> >>>> -----Original Message-----
> >> >>>> From: meta-xilinx-bounces at yoctoproject.org [mailto:meta-xilinx-
> >> >>>> bounces at yoctoproject.org] On Behalf Of Nathan Rossi
> >> >>>> Sent: Wednesday, April 26, 2017 4:57 AM
> >> >>>> To: meta-xilinx at lists.yoctoproject.org
> >> >>>> Subject: [meta-xilinx] [PATCH] machine-xilinx-default.inc: Default
> >> >>>> to u-boot for Zynq
> >> >>>>
> >> >>>> Upstream U-Boot provides an almost complete environment for the
> >> >>>> majority of Zynq targets and specifically covers all the boot
> >> >>>> functionality required for the boards in the meta-xilinx layer. As
> >> >>>> such default to
> >> >> the mainline version of U-Boot.
> >> >>>>
> >> >>>> For users that require or prefer to use u-boot-xlnx this can be
> >> >>>> selected on a per- machine basis using:
> >> >>>>
> >> >>>>   PREFERRED_PROVIDER_virtual/bootloader = "u-boot-xlnx"
> >> >>>>
> >> >>>> Signed-off-by: Nathan Rossi <nathan at nathanrossi.com>
> >> >>>> ---
> >> >>>>  conf/machine/include/machine-xilinx-default.inc | 1 +
> >> >>>>  1 file changed, 1 insertion(+)
> >> >>>>
> >> >>>> diff --git a/conf/machine/include/machine-xilinx-default.inc
> >> >>>> b/conf/machine/include/machine-xilinx-default.inc
> >> >>>> index 13e4df5746..f9e7e3a33f 100644
> >> >>>> --- a/conf/machine/include/machine-xilinx-default.inc
> >> >>>> +++ b/conf/machine/include/machine-xilinx-default.inc
> >> >>>> @@ -19,6 +19,7 @@ PREFERRED_VERSION_linux-xlnx ?= "4.6-xilinx-
> v2016.4%"
> >> >>>>
> >> >>>>  # U-Boot Configuration
> >> >>>>  XILINX_DEFAULT_UBOOT := "u-boot-xlnx"
> >> >>>> +XILINX_DEFAULT_UBOOT_zynq := "u-boot"
> >> >>>>  XILINX_DEFAULT_UBOOT_zynqmp := "u-boot"
> >> >>>
> >> >>> Why have any preferred_provider? Distro can provide these settings.
> >> >>> For ex: meta-petalinux can provide u-boot-xlnx, oe-core can provide
> >> >>> u-boot
> >> >>>
> >> >>> Any thoughts?
> >> >>
> >> >> Unfortunately not picking a provider for "virtual/bootloader" will
> >> >> result in bitbake attempting to build all providers (since
> >> >> EXTRA_IMAGEDEPENDS is depending on virtual/bootloader), as bitbake
> >> >> has no idea which one is desired (and they are all compatible).
> >> >>
> >> >> --
> >> >> NOTE: multiple providers are available for virtual/bootloader
> >> >> (u-boot-xlnx, u-boot- xlnx-dev, u-boot)
> >> >> NOTE: consider defining a PREFERRED_PROVIDER entry to match
> >> >> virtual/bootloader ...
> >> >> ERROR: Multiple .bb files are due to be built which each provide
> >> >> virtual/bootloader ...
> >> >> <various failures due to overlapping files/etc.>
> >> >> --
> >> >>
> >> >> Also note, meta-petalinux or other layers should already be able to
> >> >> override this default (by setting with ??=) either in a distro conf
> >> >> or in a machine conf e.g. zynq- generic (for meta-petalinux).
> >> >>
> >> > If this is the case then why meta-xilinx should peg to upstream u-boot by
> default?
> >> It should peg to u-boot-xlnx or linux-xlnx by default. We know that there are
> >> patches/drivers which are not upstreamed yet, and only available in Xilinx specific
> >> tree. This layer is specific to Xilinx updates and should stick to defaults supported
> by
> >> Xilinx. Other distros or layer stack which use meta-xilinx should override
> depending
> >> on their requirements not the other way round.
>
> It should be noted that Xilinx does work with upstream U-Boot, since
> Xilinx has an active maintainer (and active contributors). I would
> call that support, but that is open to your own interpretation.
>
> >> > PREFERRED_PROVIDER_virtual/bootloader = "u-boot" should be specific to
> boards
> >> other than the Xilinx eval boards, for example in zybo/microzed.
> >>
> >> I'd be happiest if meta-xilinx used upstream u-boot and a bbappend to add
> patches
> >> that are not upstream yet. This way we (the consumers) know exactly what the
> delta
> >> is to upstream.
> >>
> > Yes agreed on the methodology, that it would be the best if we maintained
> patchset on top upstream master for u-boot or kernel.
> > But currently we don't have this model, and pinning down meta-xilinx to upstream
> u-boot by default and not fetching Xilinx specific trees is not the right answer as well.
> > meta-xilinx should ideally point to Xilinx trees, we have an option either via distro
> or local.conf to change it to upstream at any given point.
> > We also can point certain evaluation boards (zybo/microzed/picozed etc) to
> upstream u-boot or kernel.
> >
> >> In this day and age, using non-mainline u-boot and kernel leads to future pain.
> (Yes, I
> >> have some old pain from using linux-xlnx)
> > I agree, but certain drivers are not up-streamed and we are doing our best to get
> them up-streamed.
>
> So the reason I have posted this patch for discussion is for this
> exact reason. Since u-boot v2017.01 (mainline), the majority of
> features and drivers are upstream (for zynq).
>
> The delta between xilinx/master
> (92e3dd638b50ad22dd90072673c80d8730903e95) and u-boot v2017.01 (which
> is the version in oe-core, as well as the base of the current
> xilinx/master) is very small for zynq.
>
> Looking at the differences, ignoring the obvious zynqmp/microblaze
> changes there are only a few features that are available in
> u-boot-xlnx that are not in mainline:
>  * partial bitstream loading support
>  * secure/encrypted bitstream loading support
>  * support for rsa verification of images
>  * board configs/devicetrees for various Xilinx internal boards
>
> Given that these features have very specific requirements, and that
> they rely on external Xilinx tools and software it is very unlikely
> that users are interested in these features by default when using
> meta-xilinx.

This is totally debatable correct?
When a feature is introduced there must have been a requirement from some set of customers for it be implemented.

 The fact that the delta is almost gone for Zynq suggests
> that Xilinx has almost achieved that goal of fully upstreaming Zynq
> support.
>
> In my opinion at least, I think that the benefits of using mainline
> u-boot now greatly out weigh the benefits of u-boot-xlnx. As such I
> think now is the best time to make this switch.
>

I disagree, meta-xilinx should not switch to mainline till delta is completely zero.
The option to switch to mainline is available either through distro or local.conf.

Thanks
Manju

> Regards,
> Nathan

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