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2024-07-25.log

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<solid_black>so Linux has added MAP_DROPPABLE
<sneek>Welcome back solid_black, you have 1 message!
<sneek>solid_black, etno says: I realize that there was probably a misunderstanding: the functions are provided by glibc, but they either return ENOSYS or -1. Detecting at build time would be error-prone (especially when cross-compiling).
<solid_black>sneek: you have taken your time relaying that to me, haven't you :)
<solid_black>etno: yes, that's how stubs work. the buildsystems still have the logic to detect such stubs, even when cross-compiling
<solid_black> https://www.mail-archive.com/qemu-devel@nongnu.org/msg1017831.html
<solid_black>so MAP_DROPPABLE can be zeroed out by the kernel at any time (under memory pressure), and is also not included in core dumps, and zeroed on fork
<solid_black>in Mach terms, that would be an (internal, temporary) vm_object whose pages never get the dirty flag set, I think?
<solid_black>plus special handling in vm_map_fork to duplicate the object instead of sharing the same pages
<etno>solid_black: 👍
<solid_black>youpi: low-priority ping