Loading modules from /boot/loader.conf

[Michael Tuexen]

> On 25. Jun 2018, at 19:17, Michael Tuexen <tuexen at FreeBSD.org> wrote:
> 
> Dear all,
> 
> I'm running FreeBSD head of today on a G4 MacMini. I'm trying to
> load a kernel module using /boot/loader.conf by having the line
> 
> tcp_rack_load="YES"
> 
> in /boot/loader.conf
> 
> However, this doesn't work and results in:
> 
> FreeBSD/powerpc Open Firmware loader, Revision 0.1
> (Tue Jun 12 01:08:20 UTC 2010 root at releng3.nyi.freebsd.org)
> Memory: 1048576KB
> Booted from: /pic at f4000000/ata- at d/disk at 0
> 
> Loading /boot/default/loader.conf
> /boot/kernel/kernel data=0x706ac+0xed588 syms=[0x4+0xa3100+0x4+0x10bc45]
> /boot/entropy size=0x1000
> /boot/kernel/tcp_rack.ko text=0x2433c data=0x1d0+0x220 syms=[0x4+0x15a0+0x4+0x17bd]
> loading required module 'kernel'
> module 'kernel' exists but with wrong version
> 
> Hit [Enter] to boot immediately, or any other key for command prompt.
> ...
> 
> I have no problems when running
> 
> kldload tcp_rack
> 
> after the system completely booted. Then the modules loads without any problems.
> 
> Any idea what am I doing wrong?
The problem seem to be in the metadata information stored in /boot/kernel/kernel.

Concentrating on the version info for the kernel.

The .symtab entry contains

entry: 11727
	st_name: _mod_metadata_kernel_version
	st_value: 0xdcafd4
	st_size: 16
	st_info: STT_OBJECT STB_LOCAL
	st_shndx: 22

which seems to be correct. However, looking at the version info, one finds:

readelf -x .data.rel.local /boot/kernel/kernel provides
  0x00dcafc8 3454f8e9 00000000 00000000 00000001 4T..............
  0x00dcafd8 00000003 00000000 00000000 02000000 ................

which corresponds to

{.md_version = 1, .md_type = 3, .md_data = NULL, .md_cval = NULL}

First of all, this information is NOT stored in the .data section as it is in
the case of power64, amd64, arm64, but in the .data.rel.local section.
Furthermore,md_data and md_cval are NULL, which should not be the case.

In addition, the set_modmetadata_set should contain pointers to the module
metadata, but it contains only NULL pointers, as can be checked with
readelf -x set_modmetadata_set /boot/kernel/kernel

Does anyone knows what is going wrong and why?

Is it possible that

https://svnweb.freebsd.org/base?view=revision&revision=268055

is related to this issue? It only handles the 64-bit version.
However, simply applying this also to __powerpc__ and recompiling
the kernel didn't solve the issue.

Best regards
Michael
> 
> Best regards
> Michael
> 
> 
> 
> 
> 
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