RFC: disallow modular framebuffers
Hi,
while looking how to fix modular FB_SAVAGE_* (both FB_SAVAGE_I2C=m and FB_SAVAGE_ACCEL=m are currently broken) I asked myself:
Do modular framebuffers really make sense?
OK, distributions like to make everything modular, but all the framebuffer drivers I've looked at parse driver specific options in their *_setup function only in the non-modular case.
And most framebuffer drivers contain a module_exit function. Is there really any case where this is both reasonable and working?
cu
Adrian
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Pearl S. Buck - Dragon SeedQuoted 10 lines · Adrian Bunk
Hi,
while looking how to fix modular FB_SAVAGE_* (both FB_SAVAGE_I2C=m and FB_SAVAGE_ACCEL=m are currently broken) I asked myself:
Do modular framebuffers really make sense?
OK, distributions like to make everything modular, but all the framebuffer drivers I've looked at parse driver specific options in their
*_setupfunction only in the non-modular case.And most framebuffer drivers contain a
module_exitfunction. Is there really any case where this is both reasonable and working?
It depends on the driver's level of hardware support, and the likely configuration of the hardware at boot time.
It is a case-by-case basis.
Jeff
The on-going work to support XGL is going to change the significance of modular framebuffers. Right now there is no real need to load framebuffers on X86. In the future XGL is probably going to require that the framebuffer be loaded. When XGL initially starts being distributed people are not going to have framebuffer loaded so modular framebuffer will let you load it on demand. From then on, in the XGL case, if framebuffers weren't modular Redhat would have to compile all 75 of them into their distro kernel.
I don't think the framebuffer codebase has received the same level of inspection that a lot of the other kernel code has. This is probably because all X86 users can currently avoid loading them due to VGA compatibility.
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Quoted 5 lines
I don't think the framebuffer codebase has received the same level of inspection that a lot of the other kernel code has. This is probably because all X86 users can currently avoid loading them due to VGA compatibility.
Actaully it has recieved inspection but we don't have the man power to clean up the system. It will always lag because of this :-(
Quoted 5 lines · Adrian Bunk
Hi,
while looking how to fix modular FB_SAVAGE_* (both FB_SAVAGE_I2C=m and FB_SAVAGE_ACCEL=m are currently broken) I asked myself:
Quoted 8 lines
Do modular framebuffers really make sense?
OK, distributions like to make everything modular, but all the framebuffer drivers I've looked at parse driver specific options in their
*_setupfunction only in the non-modular case.And most framebuffer drivers contain a
module_exitfunction. Is there really any case where this is both reasonable and working?
Only a few drivers are capable of being unloaded with the possiblity of restoring the vga console (i810fb and rivafb), when CONFIG_FBCON = n.
If CONFIG_FBCON=y, it's not possible to unload the module unless 2 drivers are loaded at the same time. One driver can be mapped to the console, so the other can be unloaded. Although not important from the user's POV, it is quite helpful when debugging/developing drivers.
Currently fbcon cannot be unloaded, it will freeze the system.
Tony
Quoted 4 lines · Adrian Bunk
Hi,
while looking how to fix modular FB_SAVAGE_* (both FB_SAVAGE_I2C=m and FB_SAVAGE_ACCEL=m are currently broken) I asked myself:
BTW, what's the problem with the above?
Tony
Quoted 7 lines · Antonino A. Daplas
Quoted 4 lines · Adrian Bunk
Hi,
while looking how to fix modular FB_SAVAGE_* (both FB_SAVAGE_I2C=m and FB_SAVAGE_ACCEL=m are currently broken) I asked myself:
BTW, what's the problem with the above?
#if defined(CONFIG_FB_SAVAGE_ACCEL)
doesn't work with FB_SAVAGE_ACCEL=m, and
#if defined(CONFIG_FB_SAVAGE_ACCEL) || defined(CONFIG_FB_SAVAGE_ACCEL_MODULE)
would break with FB_SAVAGE=y and FB_SAVAGE_ACCEL=m.
Is there any reason for these being three modules?
It seems the best solution would be to make this one module composed of up to three object files?
Quoted 1 line
Tony
cu
Adrian
Signature · 4 lines
"Is there not promise of rain?" Ling Tan asked suddenly out
of the darkness. There had been need of rain for many days.
"Only a promise," Lao Er said.
Pearl S. Buck - Dragon SeedQuoted 9 lines · Adrian Bunk
Quoted 7 lines · Antonino A. Daplas
Quoted 4 lines · Adrian Bunk
Hi,
while looking how to fix modular FB_SAVAGE_* (both FB_SAVAGE_I2C=m and FB_SAVAGE_ACCEL=m are currently broken) I asked myself:
BTW, what's the problem with the above?
Quoted 9 lines
#if defined(CONFIG_FB_SAVAGE_ACCEL)doesn't work with FB_SAVAGE_ACCEL=m, and
#if
defined(CONFIG_FB_SAVAGE_ACCEL)||defined(CONFIG_FB_SAVAGE_ACCEL_MODULE)would break with FB_SAVAGE=y and FB_SAVAGE_ACCEL=m.
I see.
Quoted 4 lines
Is there any reason for these being three modules?
It seems the best solution would be to make this one module composed of up to three object files?
Yes.
Tony
Quoted 6 lines · Antonino A. Daplas
...
Quoted 3 lines
Is there any reason for these being three modules?
It seems the best solution would be to make this one module composed of up to three object files?Yes.
Two possible solutions:
- rename savagefb.c and link the three files into savagefb.o
- merge the other two files into savagefb.c
I'd slightly prefer the first choice, but I can send patches for whichever you prefer.
As a note, in both cases the EXPORT_SYMBOL's can be removed.
Quoted 1 line
Tony
cu
Adrian
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"Is there not promise of rain?" Ling Tan asked suddenly out
of the darkness. There had been need of rain for many days.
"Only a promise," Lao Er said.
Pearl S. Buck - Dragon Seed
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http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=clickQuoted 7 lines · Adrian Bunk
Quoted 6 lines · Antonino A. Daplas
...
Quoted 3 lines
Is there any reason for these being three modules?
It seems the best solution would be to make this one module composed of up to three object files?
Quoted 8 lines
Quoted 1 line
Yes.
Two possible solutions:
- renamesavagefb.cand link the three files into savagefb.o
- merge the other two files intosavagefb.cI'd slightly prefer the first choice, but I can send patches for whichever you prefer.
I also prefer the first one even if it results into a big patch because of the rename.
Tony
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PATCH 1/1 make savagefb one module
This patch links all selected files under drivers/video/savagefb/ into one module.
This required a renaming of savagefb.c to savagefb_driver.c .
As a side effect, the EXPORT_SYMBOL's in this directory are no longer required.
---
Other names than savagefb_driver.c (e.g. savagefb_main.c) are easily possible - I do not claim being good at picking names...
Due to the size because of the renaming, this patch is attached gzipped.
drivers/video/Kconfig | 4 drivers/video/savage/Makefile | 8 drivers/video/savage/savagefb-i2c.c | 3 drivers/video/savage/savagefb.c | 2276 ------------------------- drivers/video/savage/savagefb_accel.c | 4 drivers/video/savage/savagefb_driver.c | 2276 +++++++++++++++++++++++++ 6 files changed, 2283 insertions(+), 2288 deletions(-)
Re: [Linux-fbdev-devel] [2.6 patch] make savagefb one module
Quoted 5 lines · Adrian Bunk
This patch links all selected files under
drivers/video/savagefb/into one module.This required a renaming of
savagefb.ctosavagefb_driver.c.
Quoted 7 lines
As a side effect, the EXPORT_SYMBOL's in this directory are no longer required.
---
Other names than
savagefb_driver.c(e.g.savagefb_main.c) are easily possible - I do not claim being good at picking names...
savagefb_core.c?
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]
In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that.
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Re: [Linux-fbdev-devel] [2.6 patch] make savagefb one module
Quoted 9 lines · Geert Uytterhoeven
Quoted 8 lines · Adrian Bunk
This patch links all selected files under
drivers/video/savagefb/into one module.This required a renaming of
savagefb.ctosavagefb_driver.c.As a side effect, the EXPORT_SYMBOL's in this directory are no longer required.
Quoted 6 lines
Quoted 4 lines
---
Other names than
savagefb_driver.c(e.g.savagefb_main.c) are easily possible - I do not claim being good at picking names...
savagefb_core.c?
Antonino, what's your opinion?
Quoted 3 lines
Gr{oetje,eeting}s,
Geert
cu
Adrian
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of the darkness. There had been need of rain for many days.
"Only a promise," Lao Er said.
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http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=clickRe: [Linux-fbdev-devel] [2.6 patch] make savagefb one module
Quoted 10 lines · Adrian Bunk
Quoted 9 lines · Geert Uytterhoeven
Quoted 8 lines · Adrian Bunk
This patch links all selected files under
drivers/video/savagefb/into one module.This required a renaming of
savagefb.ctosavagefb_driver.c.As a side effect, the EXPORT_SYMBOL's in this directory are no longer required.
Quoted 8 lines
Quoted 6 lines
Quoted 4 lines
---
Other names than
savagefb_driver.c(e.g.savagefb_main.c) are easily possible - I do not claim being good at picking names...
savagefb_core.c?Antonino, what's your opinion?
I'll take your patch as is.
Tony
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Quoted 10 lines · Adrian Bunk
Hi,
while looking how to fix modular FB_SAVAGE_* (both FB_SAVAGE_I2C=m and FB_SAVAGE_ACCEL=m are currently broken) I asked myself:
Do modular framebuffers really make sense?
OK, distributions like to make everything modular, but all the framebuffer drivers I've looked at parse driver specific options in their
*_setupfunction only in the non-modular case.
That sounds like it should be fixed.
Quoted 2 lines
And most framebuffer drivers contain a
module_exitfunction. Is there really any case where this is both reasonable and working?
I'd like to see them stay modular if it's not too much trouble. It makes things easier to debug and test, for one thing. I also think setups with multiple framebuffers but w/o consoles on any of them are somewhat common, meaning the fb drivers can be easily loaded and unloaded if the fb devices aren't in use.
Jesse
Quoted 2 lines · Adrian Bunk
Do modular framebuffers really make sense?
Yes. e.g., on embedded systems you may not use the display hardware (and would therefore like to save a bit of memory) but it's convenient to have only one build of the kernel/modules.
Quoted 3 lines
OK, distributions like to make everything modular, but all the framebuffer drivers I've looked at parse driver specific options in their
*_setupfunction only in the non-modular case.
Not the (new) Geode framebuffer driver -- it uses regular module parameters for this very reason.
Quoted 2 lines
And most framebuffer drivers contain a
module_exitfunction. Is there really any case where this is both reasonable and working?
It's useful for testing if nothing else. True, the Geode framebuffer driver won't restore the mode on unload but since the software VGA emulation on a Geode is less than perfect[*] I would expect people to not use vgacon and thus there's nothing really to restore.
David Vrabel
[*] I never did work out what happened to the cursor...
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Quoted 2 lines · Adrian Bunk
Do modular framebuffers really make sense?
Yes, at least these are quite common with embedded systems, quite often without fbcon. It makes little sense to keep the driver constantly loaded if the device is not being used as a console and is only seeing occasional use.
It seems more sensible to just fix up the drivers that don't do this right.. most of the broken drivers seem to be geared at x86 anyways where people generally don't seem to care.
It may not make a lot of sense with distributions on x86, though it is useful if you are doing driver development on a secondary device. This is certainly a corner case though.
Quoted 3 lines · Paul Mundt
It seems more sensible to just fix up the drivers that don't do this right.. most of the broken drivers seem to be geared at x86 anyways where people generally don't seem to care.
X86 people don't care because they have VGA (with all of it's warts). But that doesn't mean that VGA is a good thing. VGA lets X86 systems run without needing framebuffer support.
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Jon Smirl [email protected] ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click