CONFIG_XXX vs CONFIG_HAVE_XXX ?
Hi, What is the rationale behind having, for some feature XXX, both configuration macros CONFIG_XXX and CONFIG_HAVE_XXX ? For example, I'd love to use ftrace's new life-saving feature "funcgraph-retval" (which instantly shows the root cause of an error returned from a fully graphed function). Unfortunately, on all recent Debians the config says: CONFIG_HAVE_FUNCTION_GRAPH_RETVAL=y # CONFIG_FUNCTION_GRAPH_RETVAL is not set As a result, the feature is not available. Okay, I'll just enable and recompile. However, I'm wondering why in the first place such a situation is possible: what is the intention there ? Either we want the feature, or we don't (e.g. because it may incur some CPU or memory overhead), but why sit halfway in between ? Thanks in advance, -Alex
Sun, 18 May 2025 23:15:13 +0530 को alexandre.ferrieux@gmail.com ने लिखा :
What is the rationale behind having, for some feature XXX, both configuration macros CONFIG_XXX and CONFIG_HAVE_XXX ?
CONFIG_HAVE_XXX -> XXX is supported. CONFIG_XXX -> Enable XXX. XXX may not be available on an arch, for eg. Thanks, Siddh [Sorry for duplicate, pressed reply instead of reply all :P]
On Sun, May 18, 2025 at 8:25 PM Siddh Raman Pant <sanganaka@siddh.me> wrote:
Sun, 18 May 2025 23:15:13 +0530 को alexandre.ferrieux@gmail.com ने लिखा :
What is the rationale behind having, for some feature XXX, both configuration macros CONFIG_XXX and CONFIG_HAVE_XXX ?
CONFIG_HAVE_XXX -> XXX is supported. CONFIG_XXX -> Enable XXX.
XXX may not be available on an arch, for eg.
Thanks, Siddh
[Sorry for duplicate, pressed reply instead of reply all :P]
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On Sun, May 18, 2025 at 8:25 PM Siddh Raman Pant <sanganaka@siddh.me> wrote:
Sun, 18 May 2025 23:15:13 +0530 को alexandre.ferrieux@gmail.com ने लिखा :
What is the rationale behind having, for some feature XXX, both configuration macros CONFIG_XXX and CONFIG_HAVE_XXX ?
CONFIG_HAVE_XXX -> XXX is supported. CONFIG_XXX -> Enable XXX.
XXX may not be available on an arch, for eg.
Thanks, Siddh
[Sorry for duplicate, pressed reply instead of reply all :P]
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On 18/05/2025 20:22, Siddh Raman Pant wrote:
Sun, 18 May 2025 23:15:13 +0530 alexandre.ferrieux@gmail.com :
What is the rationale behind having, for some feature XXX, both configuration macros CONFIG_XXX and CONFIG_HAVE_XXX ?
CONFIG_HAVE_XXX -> XXX is supported. CONFIG_XXX -> Enable XXX.
XXX may not be available on an arch, for eg.
Ah yes, so the *_HAVE_* series are automatically-detected compatibility hints, rather than actual human-selectable configuration decisions. Makes sense, thanks! -Alex
participants (3)
-
Alexandre Ferrieux -
Mrunal Gawade -
Siddh Raman Pant