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Andrew Gabriel
*nix forums Guru
Joined: 19 Feb 2005
Posts: 454
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 Posted: Wed Feb 15, 2006 11:47 pm Post subject:
Re: Are Device Drivers Reentrant -- or Daemons?
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In article <43F3B5B7.3080400@acm.org>,
Nick Roberts <nick.roberts@acm.org> writes:
| Quote: |
I am not an expert on pthreads, but my impression is that this facility
is really rather limited. I have heard that you cannot use the semaphore
facility without running as root, and that you are limited to 32 semaphores.
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That might be a feature of some rather sad (and probably
not standards conforming) implementation, but it's certainly
not inherent in pthreads.
--
Andrew Gabriel |
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toby
*nix forums addict
Joined: 01 Jul 2005
Posts: 87
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| Posted: Thu Feb 16, 2006 4:37 am Post subject:
Re: Are Device Drivers Reentrant -- or Daemons?
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Matthias Bethke wrote:
| Quote: | begin followup to Paul Barker in comp.unix.programmer:
In linux (at least in my kernel) the folder "block" at the
root of the source tree contains all the generic block device stuff.
There may also be some good docs included with the kernel source.
There's a pretty good book by O'Reilly on Linux device drivers from
kernel 2.0 to 2.4, available on dead trees as well as free hypertext:
http://www.xml.com/ldd/chapter/book/
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The 3rd edition covers 2.6: http://lwn.net/Kernel/LDD3/
| Quote: |
cheers!
Matthias
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toby
*nix forums addict
Joined: 01 Jul 2005
Posts: 87
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| Posted: Thu Feb 16, 2006 5:07 am Post subject:
Re: Are Device Drivers Reentrant -- or Daemons?
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James Harris wrote:
| Quote: | "Chris Thompson" <cet1@cus.cam.ac.uk> wrote in message
news:dsqct8$q1r$1@gemini.csx.cam.ac.uk...
In article <dsl62m$1hvr$1@gavrilo.mtu.ru>,
Maxim S. Shatskih <maxim@storagecraft.com> wrote:
I'm not sure what 'reentrant' means here. AFAIK a program code
segment
is usually reentrant in that it cannot normally be written to - so
I'm against the whole word of ''reentrant". It is, in fact, something
from the
old time of MS-DOS add-ons which tried to do multitasking from this
pathetic
OS.
MS-DOS? That's practically yesterday! We were talking about
"reeentrant" and
"serially reusable" load modules back in OS/360, and it probably
wasn't a
new term then.
That's where I first came across the term. It was a long time ago. IIRC
it would apply to any module that did not modify part of itself.
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Before stacks became commonplace, architectural subroutine linkage
conventions (typically of the 'self-modifying' type, such as storing
the link address in a fixed location[1]) often precluded re-entrancy
and recursion except through explicit emulation of a stack.
[1] e.g. http://www.cs.clemson.edu/~mark/subroutines/pdp8.html |
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toby
*nix forums addict
Joined: 01 Jul 2005
Posts: 87
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| Posted: Thu Feb 16, 2006 5:17 am Post subject:
Re: Are Device Drivers Reentrant -- or Daemons?
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James Harris wrote:
| Quote: | "Chris Thompson" <cet1@cus.cam.ac.uk> wrote in message
news:dsqct8$q1r$1@gemini.csx.cam.ac.uk...
In article <dsl62m$1hvr$1@gavrilo.mtu.ru>,
Maxim S. Shatskih <maxim@storagecraft.com> wrote:
I'm not sure what 'reentrant' means here. AFAIK a program code
segment
is usually reentrant in that it cannot normally be written to - so
I'm against the whole word of ''reentrant". It is, in fact, something
from the
old time of MS-DOS add-ons which tried to do multitasking from this
pathetic
OS.
MS-DOS? That's practically yesterday! We were talking about
"reeentrant" and
"serially reusable" load modules back in OS/360, and it probably
wasn't a
new term then.
That's where I first came across the term. It was a long time ago. IIRC
it would apply to any module that did not modify part of itself.
|
Before stacks became an architectural commonplace, subroutine linkage
conventions (typically of the 'self-modifying' type, such as storing
the link address in a fixed location[1]) often precluded re-entrancy
and recursion by default.
As other posters point out, a stack answers both problems by providing
storage for state and return link that is local to any activation.
[1] e.g. http://www.cs.clemson.edu/~mark/subroutines/pdp8.html |
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toby
*nix forums addict
Joined: 01 Jul 2005
Posts: 87
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| Posted: Thu Feb 16, 2006 5:18 am Post subject:
Re: Are Device Drivers Reentrant -- or Daemons?
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James Harris wrote:
| Quote: | "Chris Thompson" <cet1@cus.cam.ac.uk> wrote in message
news:dsqct8$q1r$1@gemini.csx.cam.ac.uk...
In article <dsl62m$1hvr$1@gavrilo.mtu.ru>,
Maxim S. Shatskih <maxim@storagecraft.com> wrote:
I'm not sure what 'reentrant' means here. AFAIK a program code
segment
is usually reentrant in that it cannot normally be written to - so
I'm against the whole word of ''reentrant". It is, in fact, something
from the
old time of MS-DOS add-ons which tried to do multitasking from this
pathetic
OS.
MS-DOS? That's practically yesterday! We were talking about
"reeentrant" and
"serially reusable" load modules back in OS/360, and it probably
wasn't a
new term then.
That's where I first came across the term. It was a long time ago. IIRC
it would apply to any module that did not modify part of itself.
|
Before stacks became an architectural commonplace, subroutine linkage
conventions (typically of the 'self-modifying' type, such as storing
the link address in a fixed location[1]) often precluded re-entrancy
and recursion by default.
As other posters point out, a stack answers both problems by providing
storage for state and return link that is local to any activation.
[1] e.g. http://www.cs.clemson.edu/~mark/subroutines/pdp8.html |
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