Why use tristate vs bool in the Linux kernel Kconfig?
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Here is my current understanding of why one would choose to use one vs the other, can you please confirm or correct me?
- Run-time vs compile-time: If you don't know whether or not you want this enabled until run time, use tristate. Else, you know at compile time, so use bool. In the cases where you
#ifdefsome optional code A inside some surrounding code B (for example including bonus features like GPU support or something) then you would need to make A be bool, even if the entire module B could be declared as tristate, since theifdefis evaluated at compile. - Iteration speed: If you are developing a new bit of code, then if you declare it as a module then you can quickly unload the old version and reload your newly compiled version, without having to reboot the entire system.
- Intrusiveness: Some code would be so disruptive to to dynamically add to an already running kernel (e.g. Symmetric-Multi-Processing), so it is always bool.
Are there other factors I'm missing here? Factors I could see myself missing could be
- Performance
- Security
- Rules of Thumb (e.g. "Always use bool unless you need to use tristate")
Other explanations, notes, links, and thoughts would be greatly appreciated. Thanks!
linux kernel linux-kernel configuration
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Nick CrewsNick Crews
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0
Here is my current understanding of why one would choose to use one vs the other, can you please confirm or correct me?
- Run-time vs compile-time: If you don't know whether or not you want this enabled until run time, use tristate. Else, you know at compile time, so use bool. In the cases where you
#ifdefsome optional code A inside some surrounding code B (for example including bonus features like GPU support or something) then you would need to make A be bool, even if the entire module B could be declared as tristate, since theifdefis evaluated at compile. - Iteration speed: If you are developing a new bit of code, then if you declare it as a module then you can quickly unload the old version and reload your newly compiled version, without having to reboot the entire system.
- Intrusiveness: Some code would be so disruptive to to dynamically add to an already running kernel (e.g. Symmetric-Multi-Processing), so it is always bool.
Are there other factors I'm missing here? Factors I could see myself missing could be
- Performance
- Security
- Rules of Thumb (e.g. "Always use bool unless you need to use tristate")
Other explanations, notes, links, and thoughts would be greatly appreciated. Thanks!
linux kernel linux-kernel configuration
asked 1 hour ago
Nick CrewsNick Crews
1011
New contributor
Nick Crews is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
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Here is my current understanding of why one would choose to use one vs the other, can you please confirm or correct me?
- Run-time vs compile-time: If you don't know whether or not you want this enabled until run time, use tristate. Else, you know at compile time, so use bool. In the cases where you
#ifdefsome optional code A inside some surrounding code B (for example including bonus features like GPU support or something) then you would need to make A be bool, even if the entire module B could be declared as tristate, since theifdefis evaluated at compile. - Iteration speed: If you are developing a new bit of code, then if you declare it as a module then you can quickly unload the old version and reload your newly compiled version, without having to reboot the entire system.
- Intrusiveness: Some code would be so disruptive to to dynamically add to an already running kernel (e.g. Symmetric-Multi-Processing), so it is always bool.
Are there other factors I'm missing here? Factors I could see myself missing could be
- Performance
- Security
- Rules of Thumb (e.g. "Always use bool unless you need to use tristate")
Other explanations, notes, links, and thoughts would be greatly appreciated. Thanks!
linux kernel linux-kernel configuration
asked 1 hour ago
Nick CrewsNick Crews
1011
New contributor
Nick Crews is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Here is my current understanding of why one would choose to use one vs the other, can you please confirm or correct me?
- Run-time vs compile-time: If you don't know whether or not you want this enabled until run time, use tristate. Else, you know at compile time, so use bool. In the cases where you
#ifdefsome optional code A inside some surrounding code B (for example including bonus features like GPU support or something) then you would need to make A be bool, even if the entire module B could be declared as tristate, since theifdefis evaluated at compile. - Iteration speed: If you are developing a new bit of code, then if you declare it as a module then you can quickly unload the old version and reload your newly compiled version, without having to reboot the entire system.
- Intrusiveness: Some code would be so disruptive to to dynamically add to an already running kernel (e.g. Symmetric-Multi-Processing), so it is always bool.
Are there other factors I'm missing here? Factors I could see myself missing could be
- Performance
- Security
- Rules of Thumb (e.g. "Always use bool unless you need to use tristate")
Other explanations, notes, links, and thoughts would be greatly appreciated. Thanks!
linux kernel linux-kernel configuration
linux kernel linux-kernel configuration
asked 1 hour ago
Nick CrewsNick Crews
1011
New contributor
Nick Crews is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 1 hour ago
Nick CrewsNick Crews
1011
New contributor
Nick Crews is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 1 hour ago
Nick CrewsNick Crews
1011
New contributor
Nick Crews is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 1 hour ago
Nick CrewsNick Crews
1011
asked 1 hour ago
Nick CrewsNick Crews
1011
1011
New contributor
Nick Crews is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
Nick Crews is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Nick Crews is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
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