Bug#568176: memtest86+: multiboot image is broken

[Mario 'BitKoenig' Holbe]

Package: memtest86+
Version: 4.00-2.2

Hello,

when I'm booting /boot/memtest86+_multiboot.bin on a Lenovo IdeaPad S12
VIA Nano w/ 3G RAM using grub2, it reports a wrong memory information
and lots of memory errors.

To compare this against the traditional /boot/memtest86+.bin image, I
added a grub2 menu entry via /etc/grub.d/40_custom:
menuentry "Memory test (memtest86+), traditional boot" {
linux16 /boot/memtest86+.bin
}
When I'm booting this entry (which btw. works fine), everything works as
expected: memory information is displayed correctly, no errors are
shown.
Thus, I assume this issue is somehow related to the multiboot patch.

Here is what the traditional memtest86+.bin image reports as system
information:
Memtest86+ v4.00
VIA Isaiah (CN) 1596 MHz
L1 Cache: 64k 19704 MB/s
L2 Cache: 1024k 5284 MB/s
L3 Cache: None
Memory: 2814M 1471 MB/s

Here is what memtest86+_multiboot.bin reports instead (note the Memory:
line):
Memtest86+ v4.00
VIA Isaiah (CN) 1596 MHz
L1 Cache: 64k 19704 MB/s
L2 Cache: 1024k 5198 MB/s
L3 Cache: None
Memory: 640k 6514 MB/s

Thanks for your work & regards
Mario
--
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love: Avoid, if at all possible.

[Fabio Fantoni]

Hi, I'm working on a new build for debian experimental with version 5.31b

work done for now about memtest86+ package is here:
https://salsa.debian.org/debian/memtest86plus/-/commits/debian/experimental

for now multiboot patch is disabled, I don't have knowledge about
assembly and the boot part except a little something done years ago that
I hardly remember anything about, I don't have enough time recently to
read up and study the parts.

For some tests I can try to adapt the patch from coreboot that is the
most recent I found:
https://review.coreboot.org/plugins/gitiles/memtest86plus/+/8cc1aeb540a02d9600491ca5fa799b7c8f25c363
but I don't know if adapt and make it applicable and build working is
enough to have multiboot correct and don't cause bugs (from an ubuntu
issue on launchpad seems that ubuntu binaries have more issue that same
upstream version and major of source changes is multiboot patch, so can
be a cause of issue, I'm not sure)

Is there anyone with enough knowledge about it that want help me get the
correct multiboot part for 5.31b for experimental please?

[Fabio Fantoni]

today I did a fast test applying the "newer" multiboot patch I found
from coreboot repo
(https://review.coreboot.org/plugins/gitiles/memtest86plus/+/8cc1aeb540a02d9600491ca5fa799b7c8f25c363
based on Vladimir Serbinenko taken here), refreshed for 5.31b
(https://salsa.debian.org/debian/memtest86plus/-/commit/deed716beaefcd25dd676b291801df7421f1fbf0),
did also a small change to fix build fails
https://salsa.debian.org/debian/memtest86plus/-/commit/326577b966a18c7c743be36c82985f52c5155804

but testing it on one computer on multiboot entry memtest freeze always
at start, so seems another changes/fix are needed

if someone want test it:
https://salsa.debian.org/debian/memtest86plus/-/tree/multiboot-test