Daniel Eischen wrote: > > On Wed, 10 May 2006, David Xu wrote: > >> One of the problems to implement it is that atomic operations, >> if there are multiple integer needs to be updated by kernel, >> userland maybe gets an inconsistent result, the way to avoid the >> problem is using two generation numbers. >> >> http://gsu.linux.org.tr/~mpekmezci/kernelapi/unitedlinux/arch/x86_64/kernel/vsyscall.c.html >> >> check do_vgettimeofday(struct timeval * tv): >> >> Another problem is how you tell userland the address of the kernel >> page ? do you use fixed address or tell it via program headers like >> the PT_TLS set by kernel, check /usr/src/lib/libc/gen/tls.c. > > > Can you not make a simple pseudo device driver and mmap the page? > mmap is fine if you don't care binary compatible, exporting a kernel page which can be executed by userland is more flexible, kernel can change it freely without having to change libc.Received on Wed May 10 2006 - 02:01:57 UTC
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