Re: [PATCH v2 2/2] ARC: enable uboot support unconditionally

[Greg Kroah-Hartman]

On Thu, Jul 18, 2019 at 08:51:23PM +0000, Alexey Brodkin wrote:
> Hi Greg,
> 
> > -----Original Message-----
> > From: Eugeniy Paltsev <Eugeniy.Paltsev@xxxxxxxxxxxx>
> > Sent: Thursday, February 14, 2019 6:08 PM
> > To: linux-snps-arc@xxxxxxxxxxxxxxxxxxx; Vineet Gupta <vgupta@xxxxxxxxxxxx>
> > Cc: linux-kernel@xxxxxxxxxxxxxxx; Alexey Brodkin <abrodkin@xxxxxxxxxxxx>; Corentin Labbe
> > <clabbe@xxxxxxxxxxxx>; khilman@xxxxxxxxxxxx; Eugeniy Paltsev <Eugeniy.Paltsev@xxxxxxxxxxxx>
> > Subject: [PATCH v2 2/2] ARC: enable uboot support unconditionally
> > 
> > After reworking U-boot args handling code and adding paranoid
> > arguments check we can eliminate CONFIG_ARC_UBOOT_SUPPORT and
> > enable uboot support unconditionally.
> > 
> > For JTAG case we can assume that core registers will come up
> > reset value of 0 or in worst case we rely on user passing
> > '-on=clear_regs' to Metaware debugger.
> > 
> > Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@xxxxxxxxxxxx>
> 
> May we have this one back-ported to linux-4.19.y?
> 
> It was initially applied to Linus' tree during 5.0 development
> cycle [1] but was never back-ported.
> 
> Now w/o that patch in KernelCI we see boot failure on ARC HSDK
> board [2] as opposed to normally working later kernel versions.
> 
> [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=493a2f812446e92bcb1e69a77381b4d39808d730
> [2] https://storage.kernelci.org/stable/linux-4.19.y/v4.19.59/arc/hsdk_defconfig/gcc-8/lab-baylibre/boot-hsdk.txt
> 
> Below is that same patch but rebased on linux-4.19 as in its pristine
> form it won't apply due to offset of one of hunks.

Why is this patch ok for stable kernel trees?  Are you not removing
existing support in 4.19 for a feature that people might be using there?
What bug is this fixing that requires this removal?

thanks,

greg k-h