On Sun, 07 Nov 2021 03:52:13 +0200 Bohdan Horbeshko
<bodqhrohro@gmail.com> wrote:
> Package: linux-image-5.14.0-2-amd64
> Severity: minor
>
> Dear Maintainer,
>
> the Installed-Size of the package has occasionally grown up to 375 MB,
> which is about 30% larger than several minor releases before. A kindful
> anonymous person has collected some more information here:
> https://www.linux.org.ru/forum/general/16628666?cid=16628797 ;, and found
> out that virtually every module has been grown in size. So this is
> likely related to compilation options, rather than to some added modules
> as I suspected before.
>
> Please investigate the actual reason and report if this can/would be
> fixed in further packages, thanks.
[...]
The linked thread mentioned floppy.ko as an exmaple. Comparing the
versions I have installed here:
~$ ls -l /lib/modules/*/kernel/drivers/block/floppy.ko
-rw-r--r-- 1 root root 182555 Aug 3 07:50 /lib/modules/5.10.0-8-amd64/kernel/drivers/block/floppy.ko
-rw-r--r-- 1 root root 196947 Nov 26 06:33 /lib/modules/5.15.0-2-amd64/kernel/drivers/block/floppy.ko
there's about a 14 KiB increase from 5.10 to 5.15.
The code and static data sizes are roughly the same, actually slightly
smaller:
~$ size /lib/modules/*/kernel/drivers/block/floppy.ko
text data bss dec hex filename
64213 4893 14660 83766 14736 /lib/modules/5.10.0-8-amd64/kernel/drivers/block/floppy.ko
63619 4836 16516 84971 14beb /lib/modules/5.15.0-2-amd64/kernel/drivers/block/floppy.ko
The bss can be ignored as it doesn't take up disk space.
Listing the sections with "objdump -h", I see a new section in 5.15:
Idx Name Size VMA LMA File off Algn
[...]
26 .BTF 00002b58 0000000000000000 0000000000000000 00010c40 2**0
CONTENTS, READONLY
That's a size of about 11 KiB, so most of the increase.
After that I compared *all* the modules installed by these versions:
~$ du --bytes --summ /lib/modules/5.10.0-8-amd64/kernel
294650546 /lib/modules/5.10.0-8-amd64/kernel
~$ du --bytes --summ /lib/modules/5.15.0-2-amd64/kernel
371262312 /lib/modules/5.15.0-2-amd64/kernel
About a 73 MiB increase.
I calculated the total size of .BTF sections:
$ find /lib/modules/5.15.0-2-amd64/ -name '*.ko' | xargs objdump -h -j .BTF | awk 'BEGIN { total = 0 } $2 == ".BTF" { total = total + strtonum("0x" $3) } END { print total }'
objdump: Warning: Separate debug info file /usr/lib/modules/5.15.0-2-amd64/kernel/sound/usb/usx2y/snd-usb-us122l.ko found, but CRC does not match - ignoring
objdump: Warning: Separate debug info file /usr/lib/modules/5.15.0-2-amd64/kernel/drivers/leds/leds-gpio.ko found, but CRC does not match - ignoring
objdump: Warning: Separate debug info file /usr/lib/modules/5.15.0-2-amd64/kernel/fs/nls/nls_cp862.ko found, but CRC does not match - ignoring
61693267
About 59 MiB, so again most of the increase.
It appears that BTF in modules was enabled in Linux 5.11 by
<https://git.kernel.org/linus/5f9ae91f7c0dbbc4195e2a6c8eedcaeb5b9e4cbb>
I also compared the total sizes of code and static data:
$ find /lib/modules/5.10.0-8-amd64/ -name '*.ko' | xargs objdump -h | awk 'BEGIN { total = 0 } $2 ~ /^\..*(text|data)/ { total = total + strtonum("0x" $3) } END { print total }'
objdump: Warning: Separate debug info file /usr/lib/modules/5.10.0-8-amd64/kernel/sound/usb/usx2y/snd-usb-us122l.ko found, but CRC does not match - ignoring
objdump: Warning: Separate debug info file /usr/lib/modules/5.10.0-8-amd64/kernel/drivers/hid/hid-macally.ko found, but CRC does not match - ignoring
objdump: Warning: Separate debug info file /usr/lib/modules/5.10.0-8-amd64/kernel/fs/fat/vfat.ko found, but CRC does not match - ignoring
88844481
$ find /lib/modules/5.15.0-2-amd64/ -name '*.ko' | xargs objdump -h | awk 'BEGIN { total = 0 } $2 ~ /^\..*(text|data)/ { total = total + strtonum("0x" $3) } END { print total }'
objdump: Warning: Separate debug info file /usr/lib/modules/5.15.0-2-amd64/kernel/sound/usb/usx2y/snd-usb-us122l.ko found, but CRC does not match - ignoring
objdump: Warning: Separate debug info file /usr/lib/modules/5.15.0-2-amd64/kernel/drivers/leds/trigger/ledtrig-default-on.ko found, but CRC does not match - ignoring
objdump: Warning: Separate debug info file /usr/lib/modules/5.15.0-2-amd64/kernel/fs/nls/mac-roman.ko found, but CRC does not match - ignoring
93202503
About 4 MiB increase. This is probably a combination of changes in code
generation between gcc 10 and 11, increases in complexity of existing
code modules, and a few new drivers and features being enabled. Without
doing some full rebuilds it's not possible to separate these.
That leaves about 10 MiB of the increase in installed module size not
yet explained.
Ben.
--
Ben Hutchings
This sentence contradicts itself - no actually it doesn't.
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