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From: Martin Nybo Andersen <tweek@tweek.dk>
To: Tor Vic <torvic9@mailbox.org>
Cc: Masahiro Yamada <masahiroy@kernel.org>,
	Nathan Chancellor <nathan@kernel.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Nicolas Schier <nicolas@fjasle.eu>,
	Nick Terrell <terrelln@fb.com>,
	linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] Use CRC32 and a 1MiB dictionary for XZ compressed modules
Date: Fri, 22 Sep 2023 10:52:02 +0200 (CEST)	[thread overview]
Message-ID: <b85bf040-f6be-ef12-5b33-6d41991e4d97@tweek.dk> (raw)
In-Reply-To: <c2b92ff2-d077-4588-9d5c-93dfec0037ee@mailbox.org>

[-- Attachment #1: Type: text/plain, Size: 1546 bytes --]

On Fri, 22 Sep 2023, Tor Vic wrote:

>> 
>> Hello?
>
> Hello,

:)

>> Anyone?
>> 
>> Best regards,
>> - Martin
>> 
>> On Fri, 15 Sep 2023, Martin Nybo Andersen wrote:
>> 
>>> Kmod is now using the kernel decompressor which doesn't handle CRC64
>>> and dictionaries larger than 1MiB.
>>> 
>>> Fixes: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1050582
>>> Signed-off-by: Martin Nybo Andersen <tweek@tweek.dk>
>>> ---
>>> scripts/Makefile.modinst | 2 +-
>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>> 
>>> diff --git a/scripts/Makefile.modinst b/scripts/Makefile.modinst
>>> index c59cc57286ba..ffbafbd3aeea 100644
>>> --- a/scripts/Makefile.modinst
>>> +++ b/scripts/Makefile.modinst
>>> @@ -144,7 +144,7 @@ endif
>>> quiet_cmd_gzip = GZIP    $@
>>>       cmd_gzip = $(KGZIP) -n -f $<
>>> quiet_cmd_xz = XZ      $@
>>> -      cmd_xz = $(XZ) --lzma2=dict=2MiB -f $<
>>> +      cmd_xz = $(XZ) --check=crc32 --lzma2=dict=1MiB -f $<
>
> I wonder whether it should be guarded with
>    ifdef CONFIG_MODULE_DECOMPRESS
>
> But on the other hand, the difference between 1M and 2M is likely very small 
> in terms of compression ratio.

That would work, since kmod decompress the modules in userspace if 
CONFIG_MODULE_DECOMPRESS if off.

What I'm aiming for is just that the kernel should be able to decompress 
its own modules, when it advertises it.

Cheers,
Martin

> Cheers,
> Tor Vic
>
>>> quiet_cmd_zstd = ZSTD    $@
>>>       cmd_zstd = $(ZSTD) -T0 --rm -f -q $<
>>> 
>>> -- 
>>> 2.40.1
>>> 
>>> 
>> 
>
>

  reply	other threads:[~2023-09-22  8:52 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-09-15 10:15 [PATCH] Use CRC32 and a 1MiB dictionary for XZ compressed modules Martin Nybo Andersen
2023-09-22  7:45 ` Martin Nybo Andersen
2023-09-22  8:25 ` Tor Vic
2023-09-22  8:52   ` Martin Nybo Andersen [this message]
2023-09-22 10:41     ` Masahiro Yamada
2023-09-22 11:04       ` Martin Nybo Andersen
2023-09-22 13:34         ` Masahiro Yamada
2023-09-25  7:05           ` Masahiro Yamada
2023-09-22  9:16 ` Nicolas Schier

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