linux-kernel - Re: [PATCH v8 6/7] x86: Add support for ZSTD compressed kernel

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Message-ID: <CA+icZUWr0FBO1dpu-PPXJDSFzemoD7zniq+eQQrWXA_uGVKVAA@mail.gmail.com>
Date:   Fri, 24 Jul 2020 16:48:36 +0200
From:   Sedat Dilek <sedat.dilek@...il.com>
To:     Arvind Sankar <nivedita@...m.mit.edu>
Cc:     Nick Terrell <nickrterrell@...il.com>,
        Borislav Petkov <bp@...en8.de>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel@...r.kernel.org, Chris Mason <clm@...com>,
        linux-kbuild@...r.kernel.org, x86@...nel.org,
        gregkh@...uxfoundation.org, Petr Malat <oss@...at.biz>,
        Kees Cook <keescook@...omium.org>,
        Kernel Team <Kernel-team@...com>,
        Adam Borowski <kilobyte@...band.pl>,
        Patrick Williams <patrickw3@...com>, rmikey@...com,
        mingo@...nel.org, Patrick Williams <patrick@...cx.xyz>,
        Norbert Lange <nolange79@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Alex Xu <alex_y_xu@...oo.ca>, Nick Terrell <terrelln@...com>
Subject: Re: [PATCH v8 6/7] x86: Add support for ZSTD compressed kernel

On Fri, Jul 24, 2020 at 4:30 PM Arvind Sankar <nivedita@...m.mit.edu> wrote:
>
> On Fri, Jul 24, 2020 at 02:50:34AM +0200, Sedat Dilek wrote:
> > On Thu, Jul 23, 2020 at 9:30 PM Nick Terrell <nickrterrell@...il.com> wrote:
> > >
> > > From: Nick Terrell <terrelln@...com>
> > >
> > > * Add support for zstd compressed kernel
> > > * Define __DISABLE_EXPORTS in misc.c
> > > * Bump the heap size for zstd.
> > > * Update the documentation.
> > >
> > > Integrates the ZSTD decompression code to the x86 pre-boot code.
> > >
> > > Zstandard requires slightly more memory during the kernel decompression
> > > on x86 (192 KB vs 64 KB), and the memory usage is independent of the
> > > window size.
> > >
> > > __DISABLE_EXPORTS is defined in misc.c instead of the Makefile because
> > > kaslr.c defines __DISABLE_EXPORTS, and defining it in the Makefile gives
> > > duplicate definition warnings.
> > >
> >
> > That was reported by Arvind - feel free to add a Reported-by: ...
> >
> > - Sedat -
> >
>
> It's not necessary to add Reported-by's for problems encountered while
> developing the series. Especially as it was my drive-by suggestion to
> use __DISABLE_EXPORTS that introduced the issue in the first place :)
>

It is up to you with credits.

> I'd have added it to the Makefile and just dropped the definition in
> kaslr.c -- should be no reason for anything in here to use EXPORT_SYMBOL.
>

I cannot follow - this is no more needed as this was due to some of
your local changes in kaslr.c?

- Sedat -