Am 05.09.23 um 16:28 schrieb Sui Jingfeng:
Hi,
On 2023/9/5 21:28, Christian König wrote:
2) Typically, those non-86 machines don't have a good UEFI firmware
support, which doesn't support select primary GPU as firmware
stage.
Even on x86, there are old UEFI firmwares which already made
undesired
decision for you.
3) This series is attempt to solve the remain problems at the
driver level,
while another series[1] of me is target to solve the majority
of the
problems at device level.
Tested (limited) on x86 with four video card mounted, Intel UHD
Graphics
630 is the default boot VGA, successfully override by ast2400 with
ast.modeset=10 append at the kernel cmd line.
The value 10 is incredibly arbitrary, and multiplied as a magic number
all over the place.
+1
This is the exact reason why I made this series as RFC, because this
is a open-ended problem.
The choices of 3,4,5,6,7,8 and 9 are as arbitrary as the number of
'10'. '1' and '2' is
definitely not suitable, because the seat has already been taken.
Well you are completely missing the point. *DON'T* abuse the modeset
module parameters for this!
If you use 10 or any other value doesn't matter.
Regards,
Christian.
Take the drm/nouveau as an example:
```
MODULE_PARM_DESC(modeset, "enable driver (default: auto, "
"0 = disabled, 1 = enabled, 2 = headless)");
int nouveau_modeset = -1;
module_param_named(modeset, nouveau_modeset, int, 0400);
```
'1' is for enable the drm driver, some driver even override the
'nomodeset' parameter.
'2' is not suitable, because nouveau use it as headless GPU
(render-only or compute class GPU?)
'3' is also not likely the best, the concerns is that
what if a specific drm driver want to expand the usage in the future?
The reason I pick up the digit '10' is that
1) The modeset parameter is unlikely to get expanded up to 10 usages.
Other drm drivers only use the '-1', '0' and 1, choose '2' will
conflict with drm/nouveau.
By pick the digit '10', it leave some space(room) to various device
driver authors.
It also helps to keep the usage consistent across various drivers.
2) An int taken up 4 byte, I don't want to waste even a single byte,
While in the process of defencing my patch, I have to say
draft another kernel command line would cause the wasting of precious
RAM storage.
An int can have 2^31 usage, why we can't improve the utilization rate?
3) Please consider the fact that the modeset is the most common and
attractive parameter
No name is better than the 'modeset', as other name is not easy to
remember.
Again, this is for Linux user, thus it is not arbitrary.
Despite simple and trivial, I think about it more than one week.
