Re: cvs commit: src/sys/sys tls.h src/lib/libc/gen tls.c src/lib
Sorry, I was offline for a few days.
On Sun, Mar 27, 2005 at 07:33:20PM -0800, Matthew Dillon wrote:
> dillon 2005/03/27 19:33:20 PST
>
> DragonFly src repository
>
> Modified files:
> sys/sys tls.h
> lib/libc/gen tls.c
> lib/libthread_xu/arch/amd64/amd64 pthread_md.c
> lib/libthread_xu/arch/i386/i386 pthread_md.c
> libexec/rtld-elf rtld.c rtld.h rtld_tls.h
> libexec/rtld-elf/i386 reloc.c
> Log:
> Cleanup and retool portions of the TLS support and make sure that
> non-threaded binaries remain compatible with older kernels.
>
> * Removes the tcb alignment argument. Instead an alignment #define is
> placed in sys/tls.h
I'd like to get rid of the size argument too. This should be split into
machine/tls.h (with e.g. the struct tcb define) and sys/tls.h with the
general system call.
> * Gets rid of the Variant I code (we can add it in later, it just gets
> in the way).
That's why I wanted to use Variant I always. For the archive, there is one
nasty thing -- statically linked binaries. For those, ld itself does the
relocation and therefore it would have to be changed to go directly to
positive offsets.
>
> * Retools the Variant II code to support %gs:OFFSET (negative offset)
> AND %gs:0 relative accesses, supporting both -mtls-direct-seg-refs and
> -mno-tls-direct-seg-refs.
As Doug mentioned, this means m:n implementation has to do a syscall for
thread switched.
> * Changes the Elf_Addr array for the TCB into a real structure in
> sys/tls.h
There are a lot of places where Elf_Addr is used in the linker and
void * is meant. I have a patch laying around to solve that, will commit it
later.
>
> * Retains the DTV methodology.
>
> * Retains the TCB methodology, but note that the area 'after' the tcb
> is now available for future use (at least with Variant I removed).
> Frankly I'm not sure we would ever want to support having the
> 'data' area after the TCB instead of before the TCB, at least not
> for i386.
Placing the TLS area after the TCB solves a lot of nasty problems :)
Joerg
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