Re: [gentoo-user] agpgart, radeon and amdgpu kernel modules

[Michael <confabulate@kintzios.com>]

[-- Attachment #1: Type: text/plain, Size: 3921 bytes --]

On Sunday, 2 March 2025 23:08:34 Greenwich Mean Time gevisz wrote:
> I have AMD/ATI RV740 PRO [Radeon HD 4770]
> video card connected to the PCIEX16_1 port of
> my Gigabyte GA-MA790FXT-UD5P motherboard
> that has no integrated video card.
> 
> My processor is AMD Phenom II X4 945,
> and I believe that it has no integrated graphics
> card on it as well.
> 
> This my belief is based on the fact that all this
> is almost 20 years old. :)

The first K10 series APUs were launched later in the season and later on took 
off big time with the subsequent Bulldozer architecture, your K10 CPU has no 
integrated graphics cores.  If you remove your graphics card, you should 
discover your monitor remains dark.  :-)


> According to https://wiki.gentoo.org/wiki/Radeon
> I have set in my make.conf
> VIDEO_CARDS = "radeon r600"
> 
> Also the same https://wiki.gentoo.org/wiki/Radeon
> instructs: "For cards that sit in an AGP slot, enable the AGP driver."
> 
> https://uk.wikipedia.org/wiki/AGP says that PCI-Express is not AGP.
> However, lsmod currently shows me that both radeon and agpgart
> are loaded and used. Moreover, it shows that the radeon module
> uses the agpgart module.
> 
> A selected output of lsmod command is shown below.
> Module                      Size        Used by
> radeon                      1613824  9
> agpgart                     32768      2 radeon,ttm
> amdgpu                    9814016  0
> drm_suballoc_helper    12288  2 amdgpu,radeon
> i2c_algo_bit              12288     2 amdgpu,radeon
> drm_ttm_helper        12288     2 amdgpu,radeon
> ttm                            73728     3 amdgpu,radeon,drm_ttm_helper
> drm_display_helper  147456   2 amdgpu,radeon
> drm_kms_helper       55648    3 drm_display_helper,amdgpu,radeon
> drm                           520192  16
> gpu_sched,drm_kms_helper,drm_exec,drm_suballoc_helper,drm_display_helper,drm
> _buddy,amdgpu,radeon,drm_ttm_helper,ttm,amdxcp video                        
> 65536   2 amdgpu,radeon
> drm_exec                 12288   1 amdgpu
> amdxcp                    12288   1 amdgpu
> drm_buddy               16384   1 amdgpu
> gpu_sched               40960   1 amdgpu
> 
> Why? Is the apggart module really needed?
> If not, why is it loaded?
> Will the system work without it?
> Shall I exclude it from kernel config?

AGP = Accelerated Graphics Port

A high speed bus a graphics card installed in an AGP slot uses to access and 
utilise the system memory.

AGPGART = AGP Graphics Address Re-mapping Table

A table to store and swap contiguous (I think) graphics data between system 
and video memory.

Both the old AGP and the new(er) PCIe graphics cards use GART to manage 
graphics processing.


> Moreover, the same lsmod table above shows
> that the amdgpu kernel module is also loaded.
> 
> However, according to the note in
> https://wiki.gentoo.org/wiki/AMDGPU
> "Some older graphics cards are supported by both the amdgpu
> and the radeon kernel module. When using AMDGPU, it is
> recommended to unset the ATI Radeon option so that the radeon
> module is not built, or alternatively, to blacklist the radeon module
> (after rebooting check with lsmod | grep radeon to see if the
> blacklisting worked). The two modules are not meant to be loaded
> simultaneously, unless for specific systems that require it, e.g. for
> multiseat configurations."
> 
> So, the same questions about ampgpu:
> Is this module really needed? (I guess it is not needed.)
> If not, why is it loaded?
> Will the system work without it? (I guess, yes.)
> Shall I exclude it from kernel config? (I guess, yes.)
> 
> My guesses are based on the fact that the lsmod table above
> shows that amdgpu module is not used.

Have you added the amdgpu module in /etc/conf.d/modules?  Anyway, your 
graphics card uses the legacy Radeon driver and your VIDEO_CARDS entry is 
correct.  You do not need the amdgpu driver to use your Radeon HD 4770 card.

[-- Attachment #2: This is a digitally signed message part. --]
[-- Type: application/pgp-signature, Size: 833 bytes --]