Re: [9fans] interface for per process gdt manipulation

[Russ Cox <rsc@swtch.com>]

On Mon, Jun 15, 2009 at 10:37 PM, <cinap_lenrek@gmx.de> wrote:
>> i haven't looked at your code,
>> but a text interface is better than binary.
>> if you make the first field the table index number,
>> then you don't need to bother with seeking
>> to fixed offsets.  design a text format that is
>> convenient to use instead of forcing the binary
>> interface on everyone.
>
> thats a good idea. i'll look into it. should the descriptor be
> presented in a decoded/splitted up form or just be the text
> representation of the numerical values?

i would hope the former; that's what i meant by
design a text format that is convenient to use.
ideally, cat /dev/gdt should give me something
that is easily human-readable, and if i feed the
lines back into /dev/gdt one at a time
    aux/lines </dev/gdt >/dev/gdt
it should be valid input.

>> also i wonder if this should really be in
>> a separate ldt instead of polluting the gdt.
>
> older versions of glibc use an ldt entry per thread but it got
> deprecated for tls use by set_thread_area wich works only with with
> gdt entries.
>
> also ldt is not supported on amd64, but gdt segments are still
> present and used for tls on linux.

good to know; thanks.

russ