[PATCH v1] arm: add call to cleanup_before_linux for go command

[Tom Rini]

On Wed, Apr 30, 2025 at 02:31:49PM -0500, Bryan Brattlof wrote:
> On April 30, 2025 thus sayeth Bryan Brattlof:
> > On April 30, 2025 thus sayeth Tom Rini:
> > > On Wed, Apr 30, 2025 at 10:56:27PM +0530, Raghavendra, Vignesh wrote:
> > > > 
> > > > 
> > > > On 4/30/2025 10:01 PM, Tom Rini wrote:
> > > > > On Wed, Apr 30, 2025 at 11:29:04AM -0500, Bryan Brattlof wrote:
> > > > >> On April 30, 2025 thus sayeth Anshul Dalal:
> > > > >>> As discussed here[1], the go command causes undefined behavior when used
> > > > >>> for running custom OSes since the icache might hold outdated data. OSes
> > > > >>> usually also expect the MMU to be disabled upon execution.
> > > > >>>
> > > > >>> Therefore this patch adds a call to cleanup_before_linux before we jump
> > > > >>> to the loaded program/os which disables both the caches and the MMU.
> > > > >>> This makes the go command's behavior consistent with riscv platforms.
> > > > >>>
> > > > >>
> > > > >> I know quite a few other OSes are beginning to use U-Boot (QNX, 
> > > > >> GreenHills or all the other RTOSes) each with their own requirements 
> > > > >> from the bootloader. I'm curious if we should make boot* a little more 
> > > > >> generic rather than abuse the 'go' command.
> > > > 
> > > > VXworks has its own:
> > > > https://docs.u-boot.org/en/stable/usage/os/vxworks.html
> > > > 
> > > > I suppose QNX and others should ideally have their own cmds as needed.
> > > 
> > > Well, what's the QNX output file format (options?) again?
> > 
> > I've only ever seen outputs in compressed binary formats but I've been 
> > told there are tools to produce an ELF for the simulators
> > 
> 
> Ah as soon as I hit send I find it in the QNX docs[0] it's their own IFS 
> format :)
> 
> [0] https://www.qnx.com/developers/docs/7.1/#com.qnx.doc.neutrino.building/topic/intro/intro_ifs.html

I see other mentions of U-Boot in the QNX documentation and even some
forum posts that aren't 15+ years old. It would be great for someone
from QNX to chime in and explain what they recommend people do today,
and from there we can see how to improve the situation if needed.

-- 
Tom
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