Re: [PATCH 6.6 0/3] arm64: Speed up boot with faster linear map creation

[Chen-Yu Tsai]

On Tue, Feb 17, 2026 at 10:21 PM Ryan Roberts <ryan.roberts@xxxxxxx> wrote:
>
> On 17/02/2026 14:10, Greg KH wrote:
> > On Tue, Feb 17, 2026 at 01:58:36PM +0000, Ryan Roberts wrote:
> >> On 17/02/2026 13:50, Greg KH wrote:
> >>> On Tue, Feb 17, 2026 at 01:34:05PM +0000, Ryan Roberts wrote:
> >>>> Hi All,
> >>>>
> >>>> This series is a backport that applies to stable kernel 6.6 (base v6.6.126), for
> >>>> some speed ups to enable significantly faster booting on systems with a lot of
> >>>> memory. The patches were originally posted at:
> >>>>
> >>>>   https://lore.kernel.org/linux-arm-kernel/20240412131908.433043-1-ryan.roberts@xxxxxxx/
> >>>>
> >>>> ... and were originally merged upstream in v6.10-rc1.
> >>>>
> >>>> I'm requesting this be merged to stable on behalf of a partner who wants to get
> >>>> the benefit of this series in Debian 12.
> >>>
> >>> Why can't they just use a newer kernel version (i.e. 6.12)?  Surely they
> >>> would be able to justify moving to a newer kernel for performance
> >>> reasons, why enable them to stay on an older one, just delaying the
> >>> inevitable upgrade they will have to do anyway in a year or so?
> >>
> >> I can't answer this presicely, but I did ask and push for that approach. As I
> >> understand it, they are stuck with Debian 12, which is stuck with kernel 6.1.
> >> The Debian maintainer apparently requested that these go through stable in order
> >> to get them into Debian 12.
> >
> > I understand the position of Debian not wanting to take patches for new
> > features that are not already upstream, but really, Debian offers a
> > newer kernel for hardware that wants to use it for things like this,
> > right?  Why not just use that instead?
>
> Let me go push a bit harder. But I expect we are in the grey zone between bug
> and feature here; this is a performance bug fix, not a new feature. By
> selectively backporting I'm guessing they are avoiding the risk of new features
> that a new kernel brings introducing new bugs? I'm guessing there is a higher
> qualification bar for that.

Why can't they use the kernel from bookworm-backports, which is 6.12?


ChenYu