5 ms·
The exact nature of the fix is unclear at present. During dynamic linking, glibc picks a memcpy implementation which seems most appropriate for the current mac
by fweimer 3y ago
The exact nature of the fix is unclear at present.
During dynamic linking, glibc picks a memcpy implementation which seems most appropriate for the current machine. We have about 13 different implementations just for x86-64. We could add another one for current(ish) AMD CPUs, select a different existing implementation for them, or change the default for a configurable cutover point in a parameterized implementation.
- saagarjha 3y agoThis code is in the kernel, so dynamic linking and glibc is not really relevant.
- JonChesterfield 3y agoIt's the same design space. If glibc has ended up with 13 versions for x64, the kernel probably has a similar number. It's an argument by analogy for how much of an annoyance this is.
- saagarjha 3y agoNo, because the kernel has particular code size and ISA restrictions.
- fweimer 3y agoAdmittedly I had missed that. The kernel has self-patching mechanisms for doing effectively the same thing (although I don't know if it has ever been applied to memcpy before).