Re: [dpdk-dev] [EXT] Re: [PATCH] eal: change init macro as exec environment specific

[Jerin Jacob Kollanukkaran <jerinj@marvell.com>]

On Thu, 2019-03-14 at 20:44 +0000, Jerin Jacob Kollanukkaran wrote:
> On Wed, 2019-03-13 at 14:14 +0530, Jerin Jacob wrote:
> > On Wed, 2019-03-13 at 09:16 +0100, Thomas Monjalon wrote:
> > > 13/03/2019 09:02, Jerin Jacob Kollanukkaran:
> > > > On Tue, 2019-03-12 at 21:33 +0100, Thomas Monjalon wrote:
> > > > > 12/03/2019 20:25, Jerin Jacob Kollanukkaran:
> > > > > > On Fri, 2019-03-01 at 18:28 +0100, Thomas Monjalon wrote:
> > > > > > > 01/03/2019 18:05, Ferruh Yigit:
> > > > > > > > On 10/11/2017 3:33 PM, jerin.jacob at
> > > > > > > > caviumnetworks.com
> > > > > > > > (Jerin
> > > > > > > > Jacob) wrote:
> > > > > > > > > From: Thomas Monjalon <thomas at monjalon.net>
> > > > > > > > > > 07/08/2017 14:04, Jerin Jacob:
> > > > > > > > > > > baremetal execution environments may have a
> > > > > > > > > > > different
> > > > > > > > > > > method to enable RTE_INIT instead of using
> > > > > > > > > > > compiler
> > > > > > > > > > > constructor scheme. Move RTE_INIT* definition
> > > > > > > > > > > under
> > > > > > > > > > > exec-env to support different execution
> > > > > > > > > > > environments.
> > > > > > > > > > > 
> > > > > > > > > > > Signed-off-by: Jerin Jacob <jerin.jacob at
> > > > > > > > > > > caviumnetworks.com>
> > > > > > > > > > > ---
> > > > > > > > > > > 
> > > > > > > 
> > > > > > > I am not sure there is a real desire to make DPDK
> > > > > > > ready for bare-metal (back again).
> > > > > > > If any of you are aware of a real use-case, we can re-
> > > > > > > consider.
> > > > > > 
> > > > > > Some of the usecases:
> > > > > > 
> > > > > > # PCIe endpoint mode aka Smart NIC(Where DPDK runs on PCIe
> > > > > > card),
> > > > > > May
> > > > > > not need to waste one core for Linux. Specially Smart NIC
> > > > > > market
> > > > > > has
> > > > > > less number of cores.
> > > > > > On the endpoint side, It treats as FW so customer may not
> > > > > > have
> > > > > > access
> > > > > > to so nobdoy cares it is Linux or baremetal so may need to
> > > > > > waste
> > > > > > one
> > > > > > core for Linux
> > > > > > 
> > > > > > # VM case, it possible to have bare metal guest just to
> > > > > > save
> > > > > > one a
> > > > > > logical core for Linux
> > > > > > 
> > > > > > # Some of the RTOS like Zephyr already provide TCP/IP stack
> > > > > > and
> > > > > > good
> > > > > > subsystems for specific usecases.
> > > > > > 
> > > > > > # We are using DPDK for pre silicon validation for SoC
> > > > > > mode.
> > > > > > Bringing
> > > > > > up linux on emulator takes ages, Baremetal can be used for
> > > > > > Harware
> > > > > > verification too.
> > > > > > 
> > > > > > 
> > > > > > IMO, As long as it not limiting the a feature of Linux app,
> > > > > > Why
> > > > > > not
> > > > > > to
> > > > > > allow baremetal? I agree with code duplication. I think, it
> > > > > > can
> > > > > > be
> > > > > > fixed easily, Other than that, Is there any concern?
> > > > > 
> > > > > The concern is about the effort required.
> > > > > Which libc to use? Which dependency is acceptable?
> > > > 
> > > > # It should be like FreeBSD or Windows EAL port(Where changes
> > > > should be
> > > > in lib/librte_eal/xxxxxx/)
> > > > # Baremetal libc can be newlibc or musl.
> > > > # IMO, If bare metal code is open source then the dependency
> > > > does
> > > > not
> > > > matter
> > > > # if RTOS supports POSIX wrappers, the common code changes will
> > > > be
> > > > very
> > > > minimal.
> > > > # In house, We have baremetal support as PoC, where 95% of
> > > > changes
> > > > are
> > > > in lib/librte_eal/xxxxxx/ with POSIX wrappers.
> > > 
> > > Then maybe you should send your patches so we can decide if it is
> > > maintainable enough or not.
> > 
> > The  __attribute__((constructor)) only stuff we have issue to
> > support.
> > The common code changes are related to adapt
> > __attribute__((constructor)) scheme.
> > 
> > This patch will fix that issue. Other than that there is no common
> > code
> > changes.i.e everything emulated under lib/librte_eal/new_port/
> 
> Thomas,
> 
> I explained the use case and changes required. Let me know, do you
> need
> any other change on this patch to get this patch accepted?

Ping?


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