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What is the meaning of GFP

What is the meaning of GFP

Posted Mar 26, 2008 5:42 UTC (Wed) by pr1268 (subscriber, #24648)
In reply to: Atomic context and kernel API design by kjp
Parent article: Atomic context and kernel API design

My guess is "Get Free Page" (with various qualifier suffixes, i.e. GFP_KERNEL, GFP_ATOMIC, GFP_DMA, etc.).

It's strange that, after nearly an hour of grepping files throughout the entire Linux source tree, I was unable to come up with a meaning. My search took me all over the mm/, include/linux/, Documentation/, and kernel/ directories, but to no avail. The meaning of GFP_KERNEL via a Google search (going five pages deep) was equally elusive!

I suppose there are many kernel developers out there who know its true meaning whilst snickering over my frustrated search...

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What is the meaning of GFP

Posted Mar 26, 2008 8:55 UTC (Wed) by dale77 (guest, #1490) [Link]

Oops. But that is the guy who wrote about that in_atomic ref. Perhaps we need another opinion

Just kidding. Keep up the good work corbet.

Get Free Page

Posted Mar 26, 2008 10:02 UTC (Wed) by pr1268 (subscriber, #24648) [Link]

I was right! And to think I extrapolated "get free page" from the context of where I found a bunch of GFP_* macros in my search. Thank you, Dale77.

For those with further interest, the GFP_* macros appear to be a set of bitmasks, many of which are defined as bitwise-ORed versions of others (ref. <Linux source>/include/kernel/gfp.h). These are used to set parameters to allocating virtual memory (and what to do in case of failure). But, I'm certain a lot of LWN readers already know this.

I have a lot to learn about the internal workings of the Linux kernel, as well as my online search skills--I'm certain a search here at LWN would have led me to that link.

Get Free Page

Posted Mar 26, 2008 12:08 UTC (Wed) by jzbiciak (subscriber, #5246) [Link]

Google's "site:" feature is very handy. For example, to search just LWN, put "" at the start of your search string, like this.

What is the meaning of GFP

Posted Mar 31, 2008 7:43 UTC (Mon) by jengelh (subscriber, #33263) [Link]

Well on Windows you get General Protection Faults, in Linux it must therefore be General Fault
Protection :-)

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