From: Charles Forsyth <charles.forsyth@gmail.com>
To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net>
Subject: Re: [9fans] extern register
Date: Sat, 19 Jul 2014 13:42:52 +0100 [thread overview]
Message-ID: <CAOw7k5hi4bL=rVMi2Tkhtet6J_VjuD0VVMtyjCJNx0aNUBQ1og@mail.gmail.com> (raw)
In-Reply-To: <ff0d3b569d90e25239067a766a061332@felloff.net>
[-- Attachment #1: Type: text/plain, Size: 666 bytes --]
On 19 July 2014 02:57, <cinap_lenrek@felloff.net> wrote:
> would it make sense to save and restore the two registers
> on syscall entry/exit, so userspace programs could make use
> of them for per process data?
>
Good question. None of the others need to be saved and restored because
they are defined to be dead on entry to a function,
but you're right that rule doesn't really apply to extern register, and
they could be useful. _tos only works when every process has
at least one stack always at the same fixed virtual address. On the other
hand, a kernel that provides an alternative to that would
also know to save and restore extern registers.
[-- Attachment #2: Type: text/html, Size: 1118 bytes --]
next prev parent reply other threads:[~2014-07-19 12:42 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-19 1:57 cinap_lenrek
2014-07-19 2:04 ` erik quanstrom
2014-07-19 2:19 ` erik quanstrom
2014-07-19 2:33 ` cinap_lenrek
2014-07-19 2:37 ` erik quanstrom
2014-07-19 2:27 ` cinap_lenrek
2014-07-19 2:41 ` erik quanstrom
2014-07-19 12:29 ` Aram Hăvărneanu
2014-07-19 12:42 ` Charles Forsyth [this message]
2014-07-19 14:38 ` Aram Hăvărneanu
2014-07-19 14:55 ` erik quanstrom
2014-07-19 15:53 ` Aram Hăvărneanu
2014-07-20 1:42 ` cinap_lenrek
2014-07-20 10:12 ` Aram Hăvărneanu
2014-07-20 16:35 ` cinap_lenrek
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CAOw7k5hi4bL=rVMi2Tkhtet6J_VjuD0VVMtyjCJNx0aNUBQ1og@mail.gmail.com' \
--to=charles.forsyth@gmail.com \
--cc=9fans@9fans.net \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).