Re: [PATCH] erofs: fix EROFS_FS_ZIP_LZMA_DEFAULT_MAX_STREAMS on some UP platforms

[Gao Xiang]

On Mon, Aug 17, 2026 at 11:21:33AM +0200, Geert Uytterhoeven wrote:
> Hi Gao,
> 
> On Mon, 17 Aug 2026 at 11:05, Gao Xiang <xiang@xxxxxxxxxx> wrote:
> > On Mon, Aug 17, 2026 at 10:43:34AM +0200, Geert Uytterhoeven wrote:
> > > > > > In principle, that would be better, but may I ask if there is some
> > > > > > severe consequences out of one extra line of
> > > > > > CONFIG_EROFS_FS_ZIP_LZMA_DEFAULT_MAX_STREAMS=1?
> > > > > >
> > > > > > Since it has been fixed for many times, I hope if it could be improved
> > > > > > later if no severe impacts, sigh..
> > > > >
> > > > > It causes more churn (defconfig updates), and makes the defconfig
> > > > > files larger than needed.
> > > >
> > > > Could you submit a formal patch directly (since you found it and
> > > > suggested a version)?
> > > >
> > > > so I could submit it along with the pull request if you're fine with it.
> > >
> > > Will do, I want to do a bit more testing first...
> >
> > Ok, anyway, I will try to submit a PR hours later.
> > if there is a patch, the worst case is that it's included in
> > the follow-up pull request.
> >
> > > In addition, usability can be improved by hiding the prompt on UP
> > > systems:
> > >
> > > -       int "EROFS LZMA default maximum decompression streams"
> > > +       int "EROFS LZMA default maximum decompression streams" if SMP
> > >
> >
> > I hope CONFIG_EROFS_FS_ZIP_LZMA_DEFAULT_MAX_STREAMS is a user-visible
> > configuration (and the Kconfig text helps too) no matter the platform
> > is UP or not (but it can be omitted in .config) even there is the only
> > one choice in menuconfig for example on UP platforms.
> 
> Why do you prefer it to be a user-visible option on UP?
> In general, we try not to bother the user with questions about
> configuration options that do not matter for him, or that offer only
> a single valid answer.
> 
> IMHO even "if SMP && EXPERT" would make sense...

I think users should not be bothered with !SMP in the beginning.

CONFIG_EROFS_FS_ZIP_LZMA_DEFAULT_MAX_STREAMS impacts the default
LZMA maximum memory usage, I hope it shows the same for both SMP or
!SMP (even it cannot be configured on !SMP, since it clearly shows
to users the number and indicates how the default LZMA stream
derives in general.)

I think it's unlike something that is totally disabled in !SMP (or
does't have such functionality in SMP), I think that is more sense
to hide it in the configuration but here the DEFAULT_MAX_STREAM is still
meaningful and is 1.

Thanks,
Gao Xiang

> 
> Gr{oetje,eeting}s,
> 
>                         Geert
> 
> -- 
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
> 
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                 -- Linus Torvalds
>