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

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Message-ID: <20200724143022.GA601509@rani.riverdale.lan>
Date:   Fri, 24 Jul 2020 10:30:22 -0400
From:   Arvind Sankar <nivedita@...m.mit.edu>
To:     Sedat Dilek <sedat.dilek@...il.com>
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>,
        Arvind Sankar <nivedita@...m.mit.edu>,
        Nick Terrell <terrelln@...com>
Subject: Re: [PATCH v8 6/7] x86: Add support for ZSTD compressed kernel

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 :)

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.

Thanks.