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lefsha
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 Posted: Fri Sep 11, 2009 11:02 am Post subject: EMBEDDED option in kernel config |
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Manual says:
| Quote: | EMBEDDED — Configure standard kernel features (for small systems)
Description
This option allows certain base kernel options and settings to be disabled or tweaked. This is for specialized environments that can tolerate a "non-standard" kernel. This is recommend only for experts, as it is very easy to change the options to create a kernel that will not even boot properly.
On it's own, this option does not do anything except allow you to select other options.
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But at the same time it's forced on by default.
Any reason for that? Can one disable it? And how?
There are some other such options. Like AGP etc. So that is only an example.
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Lefsha
Last edited by lefsha on Fri Sep 11, 2009 12:44 pm; edited 3 times in total |
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ToeiRei
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| Posted: Fri Sep 11, 2009 11:13 am Post subject: |
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Feel free to disable it.
It is an option to strip down the kernel to the absolute minimum.
Rei
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lefsha
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| Posted: Fri Sep 11, 2009 12:41 pm Post subject: |
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| ToeiRei wrote: | Feel free to disable it.
It is an option to strip down the kernel to the absolute minimum.
Rei |
You haven't got my point. It can't be disabled! That's the point!
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dmpogo
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| Posted: Fri Sep 11, 2009 2:33 pm Post subject: |
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| ToeiRei wrote: | Feel free to disable it.
It is an option to strip down the kernel to the absolute minimum.
Rei |
It is just an option to open the choice for fine-grain management of the kernel. So embedded is a bit a misnomer, but it came from the idea that only embedded people would want to play with the options that it hides. |
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dmpogo
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| Posted: Fri Sep 11, 2009 2:35 pm Post subject: |
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| lefsha wrote: | | ToeiRei wrote: | Feel free to disable it.
It is an option to strip down the kernel to the absolute minimum.
Rei |
You haven't got my point. It can't be disabled! That's the point! |
In the kernel configuration, whenever some option can't be changed, that means that some other option forces it into particular state.
If you hit 'Help' tab while the option is selected, it will give you a description what otther options will force it.
Hm, 'configure standard features for small systems' seems does not have this description.
BTW, AGP is forced by IOMMU (even if you don't have AGP hardware on your system, IOMMU implementation requires AGP kernel infrastructure).
IOMMU in turn can only be disabled if 'configure standard features for small systems' is selected. |
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lefsha
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| Posted: Fri Sep 11, 2009 2:48 pm Post subject: |
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no text
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Lefsha
Last edited by lefsha on Fri Sep 11, 2009 2:57 pm; edited 1 time in total |
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lefsha
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| Posted: Fri Sep 11, 2009 2:56 pm Post subject: |
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| dmpogo wrote: |
In the kernel configuration, whenever some option can't be changed, that means that some other option forces it into particular state. |
That is not the case for EMBEDDED !
| dmpogo wrote: |
BTW, AGP is forced by IOMMU (even if you don't have AGP hardware on your system, IOMMU implementation requires AGP kernel infrastructure).
IOMMU in turn can only be disabled if 'configure standard features for small systems' is selected. |
That is wrong too. IOMMU is not accessible from "make menuconfig". It's turned on by default and nothing
can turn it back off.
That is why my question arised about such strange options in the kernel config.
I haven't found any info about it on the net. No explanation why it was done in that way.
Nothing how change it back.
But I clearly remember that in some older kernel versions there were no such things.
They started to came up quite recently.
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dmpogo
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| Posted: Fri Sep 11, 2009 2:58 pm Post subject: |
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| lefsha wrote: |
That is not the case for EMBEDDED ! |
I noticed and even edited my post in a meantime 
I actually never saw that particular option being forced. In principle by itself it does not matter, since it just opens other options and that's all its role.
But I understand the desire to have clean config.
One way - go to the source and find Kconfig file where it resides and see if it can be forced (perhaps it is just Help what is not complete).
Well I don't see anything that can forces it
in init/Kconfig it ijust that
menuconfig EMBEDDED
bool "Configure standard kernel features (for small systems)"
help
This option allows certain base kernel options and settings
to be disabled or tweaked. This is for specialized
environments which can tolerate a "non-standard" kernel.
Only use this if you really know what you are doing.
so it just sets the parameter EMBEDDED which is checked by other options. It does not have any 'depend' statements
If you do make menuconfig, how is the General Setup section looks like in regrad to this option ? |
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lefsha
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| Posted: Fri Sep 11, 2009 3:00 pm Post subject: |
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| dmpogo wrote: | | ToeiRei wrote: | Feel free to disable it.
It is an option to strip down the kernel to the absolute minimum.
Rei |
It is just an option to open the choice for fine-grain management of the kernel. So embedded is a bit a misnomer, but it came from the idea that only embedded people would want to play with the options that it hides. |
Exactly. That is why I'd like to turn it off. Most of the users don't use embedded on desktop...
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lefsha
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| Posted: Fri Sep 11, 2009 3:05 pm Post subject: |
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| dmpogo wrote: | | lefsha wrote: |
That is not the case for EMBEDDED ! |
I noticed and even edited my post in a meantime
I actually never saw that particular option being forced. In principle by itself it does not matter, since it just opens other options and that's all its role. |
That is wrong too. There are a number of options which are enabled only because EMBEDDED is also enabled.
Even some debugging. Which I don't need on production machine.
| dmpogo wrote: | | If you do make menuconfig, how is the General Setup section looks like in regrad to this option ? |
| Code: | --- Configure standard kernel features (for small systems)
-*- Load all symbols for debugging/ksymoops |
| Code: | CONFIG_KALLSYMS:
Say Y here to let the kernel print out symbolic crash information and
symbolic stack backtraces. This increases the size of the kernel
somewhat, as all symbols have to be loaded into the kernel image.
Symbol: KALLSYMS [=y]
Prompt: Load all symbols for debugging/ksymoops
Defined at init/Kconfig:786
Depends on: EMBEDDED |
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dmpogo
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| Posted: Fri Sep 11, 2009 3:07 pm Post subject: |
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| lefsha wrote: |
| dmpogo wrote: |
BTW, AGP is forced by IOMMU (even if you don't have AGP hardware on your system, IOMMU implementation requires AGP kernel infrastructure).
IOMMU in turn can only be disabled if 'configure standard features for small systems' is selected. |
That is wrong too. IOMMU is not accessible from "make menuconfig". It's turned on by default and nothing
can turn it back off.
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Sure, it can. It is turned off on all my machines
| Code: |
$ grep IOMMU .config
# CONFIG_GART_IOMMU is not set
# CONFIG_CALGARY_IOMMU is not set
# CONFIG_AMD_IOMMU is not set
CONFIG_IOMMU_HELPER=y
# CONFIG_IOMMU_API is not set
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we read from the flag description
Symbol: GART_IOMMU [=n]
│ Prompt: GART IOMMU support
│ Defined at arch/x86/Kconfig:582
│ Depends on: X86_64 && PCI && EMBEDDED
│ Location:
│ -> Processor type and features
│ Selects: SWIOTLB && AGP
and in arch/x86/Kconfig
| Code: |
config GART_IOMMU
bool "GART IOMMU support" if EMBEDDED
based hardware IOMMU and a software bounce buffer based IOMMU used
device) unless CONFIG_IOMMU_DEBUG or iommu=force is specified
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so if EMBEDDED is NOT set, this option is not given in menuconfig, but if EMBEDDED is set, it is given and GART_IOMMU can be disabled. |
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lefsha
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| Posted: Fri Sep 11, 2009 3:13 pm Post subject: |
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| dmpogo wrote: |
so if EMBEDDED is NOT set, this option is not given in menuconfig, but if EMBEDDED is set, it is given and GART_IOMMU can be disabled. |
I don't see this option in my config! Where it's located?
My problem is that is not only can't be seen, but also enabled! And I can't do anything about it.
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Lefsha
Last edited by lefsha on Fri Sep 11, 2009 3:16 pm; edited 1 time in total |
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dmpogo
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| Posted: Fri Sep 11, 2009 3:14 pm Post subject: |
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| Quote: |
That is wrong too. There are a number of options which are enabled only because EMBEDDED is also enabled.
Even some debugging. Which I don't need on production machine.
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You are mostly *) wrong here, EMBEDDED does not turn that options on. It SHOWS them. Without EMBEDDED these option are on, but hidden. EMBEDDED opens them up for configuration for people who needs that.
*) of course if you had EMBEDDED on, played with some options that appeared, then switched it off, the options it hides return to their default state.
Last edited by dmpogo on Fri Sep 11, 2009 3:22 pm; edited 1 time in total |
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lefsha
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| Posted: Fri Sep 11, 2009 3:21 pm Post subject: |
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| dmpogo wrote: | | Quote: |
That is wrong too. There are a number of options which are enabled only because EMBEDDED is also enabled.
Even some debugging. Which I don't need on production machine.
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You are mostly *) wrong here, EMBEDDED does not turn that options on. It SHOWS them. Without EMBEDDED these option are on, but hidden. EMBEDDED opens them up for configuration for people who needs that.
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But because of this option (IOMMU) I have AGP (stack) available and compiled into kernel.
I have no AGP. I see no reason do that for all boxes in the world...
| dmpogo wrote: |
*) I can vouch yet that there is no options that change state with EMBEDDED on, but all I know just sit in their default state and EMBEDDED make then editable |
That is why I'm asking where is it located?
I have EMBEDDED enabled by default and should be able at least to see this option, right?
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dmpogo
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| Posted: Fri Sep 11, 2009 3:25 pm Post subject: |
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It is in the General Setup (the first line of the first screen of menuconfig)
But let me repeat, with EMBEDDED set you can have leaner kernel that with unset. unset EMBEDDED leaves many options in their default 'on' position, as for example GART_IOMMU.
BTW, on you hardware you may need GART_IOMMU, (and then you have to live with AGP) I can't tell |
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lefsha
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| Posted: Fri Sep 11, 2009 3:39 pm Post subject: |
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Definitely not on the first line:
| Code: | | [*] Prompt for development and/or incomplete code/drivers |
But OK. I see anyway that not possible to do anything about it.
Thank you.
Many questions to kernel developers remain ...
But we have no other kernel available besides linux.
I have to live with that.
I'm just wondering why the hell there is no explanation about this mess.
No single word.
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dmpogo
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| Posted: Fri Sep 11, 2009 3:42 pm Post subject: |
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| lefsha wrote: | Definitely not on the first line:
| Code: | | [*] Prompt for development and/or incomplete code/drivers |
But OK. I see anyway that not possible to do anything about it.
Thank you.
Many questions to kernel developers remain ...
But we have no other kernel available besides linux.
I have to live with that.
I'm just wondering why the hell there is no explanation about this mess.
No single word. |
Come on, I said General Setup is on the first line, not first line in General Setup.
In General setup your option is in the middle, just next after 'Optimize for Size' |
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dmpogo
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| Posted: Fri Sep 11, 2009 5:06 pm Post subject: |
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| lefsha wrote: |
Many questions to kernel developers remain ...
But we have no other kernel available besides linux.
I have to live with that.
I'm just wondering why the hell there is no explanation about this mess.
No single word. |
Вы все-таки так не переживайте |
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lefsha
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| Posted: Sat Sep 12, 2009 10:42 pm Post subject: |
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| dmpogo wrote: |
Come on, I said General Setup is on the first line, not first line in General Setup.
In General setup your option is in the middle, just next after 'Optimize for Size' |
You didn't got it. I ment the option IOMMU...
That what you talking about is EMBEDDED. Of course I see it.
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dmpogo
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| Posted: Tue Sep 15, 2009 9:05 pm Post subject: |
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| lefsha wrote: | | dmpogo wrote: |
Come on, I said General Setup is on the first line, not first line in General Setup.
In General setup your option is in the middle, just next after 'Optimize for Size' |
You didn't got it. I ment the option IOMMU...
That what you talking about is EMBEDDED. Of course I see it. |
When EMBEDDED is set, IOMMU option appears in Processor Type and Features, just after Processor Family.
It is called 'GART IOMMU Support' |
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