* Re: problem with cygwin version of egcs
@ 1999-03-08 16:55 Earnie Boyd
[not found] ` < 19990309005620.2525.rocketmail@send102.yahoomail.com >
1999-03-31 19:45 ` Earnie Boyd
0 siblings, 2 replies; 10+ messages in thread
From: Earnie Boyd @ 1999-03-08 16:55 UTC (permalink / raw)
To: DJ Delorie; +Cc: cygwin
---DJ Delorie <dj@delorie.com> wrote:
>
>
> > Beginning with version b20 the cygwin package was built optimized
for
> > i586. This means that you will not be able to successfully use it
on
> > a lesser machine.
>
> Not true. It will run on a 486. It's just optimized for the 586's
> timings.
>
Showing my ignorance here, can you explain in more detail?
==
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* Re: problem with cygwin version of egcs
[not found] ` < 19990309005620.2525.rocketmail@send102.yahoomail.com >
@ 1999-03-08 17:07 ` DJ Delorie
1999-03-31 19:45 ` DJ Delorie
0 siblings, 1 reply; 10+ messages in thread
From: DJ Delorie @ 1999-03-08 17:07 UTC (permalink / raw)
To: earnie_boyd; +Cc: cygwin
> Showing my ignorance here, can you explain in more detail?
To make up an example, consider the JCXZ instruction - jump if CX is
zero. On older CPUs, it was faster than the corresponding risc-like
options. This chart shows the number of clocks used if the jump is
taken:
8086 80486
JCXZ foo 16 8
CMP CX,0 4 1
JZ foo 16 3
OR CX,CX 3 1
JZ foo 16 3
As you can see, on the 8086 it's faster to use JCXZ but on the 80486,
it's faster to use separate compare and jump instructions.
Newer processors optimized the common instructions (mov, or, cmp, jz)
so much that it's now faster to use them than the single JCXZ
instruction. So, if you're planning on running on an old machine,
you'd want one set of instructions, but if you're running on a newer
machine, you'd want a different set. Both sets will work perfectly
well on either machine, but different ones are optimal depending on
the machine chosen. The gcc switch to select 386 vs 486 vs 586 does
exactly that - it chooses among equally functional alternatives based
on which is expected to perform better on the indicated platform.
Note that this does *not* mean that gcc can't choose to use
instructions that won't run on older machines - it certainly has that
option if the gcc programmers have added it. For example, the 486 has
added various bit test instructions that gcc may know about (I don't
know). However, the option to enable these extra opcodes is not the
one that we're talking about here, if such an option exists at all.
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* Re: problem with cygwin version of egcs
1999-03-08 17:07 ` DJ Delorie
@ 1999-03-31 19:45 ` DJ Delorie
0 siblings, 0 replies; 10+ messages in thread
From: DJ Delorie @ 1999-03-31 19:45 UTC (permalink / raw)
To: earnie_boyd; +Cc: cygwin
> Showing my ignorance here, can you explain in more detail?
To make up an example, consider the JCXZ instruction - jump if CX is
zero. On older CPUs, it was faster than the corresponding risc-like
options. This chart shows the number of clocks used if the jump is
taken:
8086 80486
JCXZ foo 16 8
CMP CX,0 4 1
JZ foo 16 3
OR CX,CX 3 1
JZ foo 16 3
As you can see, on the 8086 it's faster to use JCXZ but on the 80486,
it's faster to use separate compare and jump instructions.
Newer processors optimized the common instructions (mov, or, cmp, jz)
so much that it's now faster to use them than the single JCXZ
instruction. So, if you're planning on running on an old machine,
you'd want one set of instructions, but if you're running on a newer
machine, you'd want a different set. Both sets will work perfectly
well on either machine, but different ones are optimal depending on
the machine chosen. The gcc switch to select 386 vs 486 vs 586 does
exactly that - it chooses among equally functional alternatives based
on which is expected to perform better on the indicated platform.
Note that this does *not* mean that gcc can't choose to use
instructions that won't run on older machines - it certainly has that
option if the gcc programmers have added it. For example, the 486 has
added various bit test instructions that gcc may know about (I don't
know). However, the option to enable these extra opcodes is not the
one that we're talking about here, if such an option exists at all.
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^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: problem with cygwin version of egcs
1999-03-08 16:55 problem with cygwin version of egcs Earnie Boyd
[not found] ` < 19990309005620.2525.rocketmail@send102.yahoomail.com >
@ 1999-03-31 19:45 ` Earnie Boyd
1 sibling, 0 replies; 10+ messages in thread
From: Earnie Boyd @ 1999-03-31 19:45 UTC (permalink / raw)
To: DJ Delorie; +Cc: cygwin
---DJ Delorie <dj@delorie.com> wrote:
>
>
> > Beginning with version b20 the cygwin package was built optimized
for
> > i586. This means that you will not be able to successfully use it
on
> > a lesser machine.
>
> Not true. It will run on a 486. It's just optimized for the 586's
> timings.
>
Showing my ignorance here, can you explain in more detail?
==
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-------------------o0O0--Earnie--0O0o-------------------
-- earnie_boyd@yahoo.com --
-- http://www.freeyellow.com/members5/gw32/index.html --
----------------------ooo0O--O0ooo----------------------
PS: Newbie's, you should visit my page.
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^ permalink raw reply [flat|nested] 10+ messages in thread
* problem with cygwin version of egcs
1999-03-08 11:26 John McNally
@ 1999-03-31 19:45 ` John McNally
0 siblings, 0 replies; 10+ messages in thread
From: John McNally @ 1999-03-31 19:45 UTC (permalink / raw)
To: cygwin
I am running cygwin b20.1 with win95 on a 486. I installed the version
of egcs1.1.1 for cygwin b20.
When trying to run g77 (or gcc) I get
This program cannot be run in DOS mode.
Other b20 utils like "ls" and "du" work. I did not check b20 version of
gcc before overlaying egcs version. I have looked in the cygwin mailing
list archives and didn't find anything. And I'm not sure it would be
discussed wrt egcs.
Has anyone else reported this problem? This is the sort of error
message associated with trying to run a windows program from a DOS box,
which is not what I think I'm doing. I don't know much about this.
Just trying to run g77 and b19 version tends to freeze up occasionally.
Thought I'd try an update. B19 still works thankfully.
--
John McNally
Graduate Student, UCLA
Graduate Student Researcher,
UC-Davis/LLNL
P.O. Box 808, L-543
Livermore, CA 94550
voice: (925) 424-5113
FAX: (925) 424-5114
e-mail: mcnally@tempest.engr.ucdavis.edu
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^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: problem with cygwin version of egcs
1999-03-08 12:06 ` DJ Delorie
@ 1999-03-31 19:45 ` DJ Delorie
0 siblings, 0 replies; 10+ messages in thread
From: DJ Delorie @ 1999-03-31 19:45 UTC (permalink / raw)
To: earnie_boyd; +Cc: cygwin
> Beginning with version b20 the cygwin package was built optimized for
> i586. This means that you will not be able to successfully use it on
> a lesser machine.
Not true. It will run on a 486. It's just optimized for the 586's
timings.
--
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^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: problem with cygwin version of egcs
1999-03-08 11:36 Earnie Boyd
[not found] ` < 19990308193738.13807.rocketmail@send102.yahoomail.com >
@ 1999-03-31 19:45 ` Earnie Boyd
1 sibling, 0 replies; 10+ messages in thread
From: Earnie Boyd @ 1999-03-31 19:45 UTC (permalink / raw)
To: John McNally, cygwin
Beginning with version b20 the cygwin package was built optimized for
i586. This means that you will not be able to successfully use it on
a lesser machine. You could get version b19 and the b20 sources and
build it optimized for i486 and you should then be able to use it or
cross-compile from linux.
---John McNally <mcnally@tempest.engr.ucdavis.edu> wrote:
>
> I am running cygwin b20.1 with win95 on a 486. I installed the
version
> of egcs1.1.1 for cygwin b20.
> When trying to run g77 (or gcc) I get
>
> This program cannot be run in DOS mode.
>
> Other b20 utils like "ls" and "du" work. I did not check b20
version of
> gcc before overlaying egcs version. I have looked in the cygwin
mailing
> list archives and didn't find anything. And I'm not sure it would be
> discussed wrt egcs.
>
> Has anyone else reported this problem? This is the sort of error
> message associated with trying to run a windows program from a DOS
box,
> which is not what I think I'm doing. I don't know much about this.
> Just trying to run g77 and b19 version tends to freeze up
occasionally.
> Thought I'd try an update. B19 still works thankfully.
> --
> John McNally
> Graduate Student, UCLA
> Graduate Student Researcher,
> UC-Davis/LLNL
> P.O. Box 808, L-543
> Livermore, CA 94550
> voice: (925) 424-5113
> FAX: (925) 424-5114
> e-mail: mcnally@tempest.engr.ucdavis.edu
>
> --
> Want to unsubscribe from this list?
> Send a message to cygwin-unsubscribe@sourceware.cygnus.com
>
>
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^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: problem with cygwin version of egcs
[not found] ` < 19990308193738.13807.rocketmail@send102.yahoomail.com >
@ 1999-03-08 12:06 ` DJ Delorie
1999-03-31 19:45 ` DJ Delorie
0 siblings, 1 reply; 10+ messages in thread
From: DJ Delorie @ 1999-03-08 12:06 UTC (permalink / raw)
To: earnie_boyd; +Cc: cygwin
> Beginning with version b20 the cygwin package was built optimized for
> i586. This means that you will not be able to successfully use it on
> a lesser machine.
Not true. It will run on a 486. It's just optimized for the 586's
timings.
--
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Send a message to cygwin-unsubscribe@sourceware.cygnus.com
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: problem with cygwin version of egcs
@ 1999-03-08 11:36 Earnie Boyd
[not found] ` < 19990308193738.13807.rocketmail@send102.yahoomail.com >
1999-03-31 19:45 ` Earnie Boyd
0 siblings, 2 replies; 10+ messages in thread
From: Earnie Boyd @ 1999-03-08 11:36 UTC (permalink / raw)
To: John McNally, cygwin
Beginning with version b20 the cygwin package was built optimized for
i586. This means that you will not be able to successfully use it on
a lesser machine. You could get version b19 and the b20 sources and
build it optimized for i486 and you should then be able to use it or
cross-compile from linux.
---John McNally <mcnally@tempest.engr.ucdavis.edu> wrote:
>
> I am running cygwin b20.1 with win95 on a 486. I installed the
version
> of egcs1.1.1 for cygwin b20.
> When trying to run g77 (or gcc) I get
>
> This program cannot be run in DOS mode.
>
> Other b20 utils like "ls" and "du" work. I did not check b20
version of
> gcc before overlaying egcs version. I have looked in the cygwin
mailing
> list archives and didn't find anything. And I'm not sure it would be
> discussed wrt egcs.
>
> Has anyone else reported this problem? This is the sort of error
> message associated with trying to run a windows program from a DOS
box,
> which is not what I think I'm doing. I don't know much about this.
> Just trying to run g77 and b19 version tends to freeze up
occasionally.
> Thought I'd try an update. B19 still works thankfully.
> --
> John McNally
> Graduate Student, UCLA
> Graduate Student Researcher,
> UC-Davis/LLNL
> P.O. Box 808, L-543
> Livermore, CA 94550
> voice: (925) 424-5113
> FAX: (925) 424-5114
> e-mail: mcnally@tempest.engr.ucdavis.edu
>
> --
> Want to unsubscribe from this list?
> Send a message to cygwin-unsubscribe@sourceware.cygnus.com
>
>
_________________________________________________________
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^ permalink raw reply [flat|nested] 10+ messages in thread
* problem with cygwin version of egcs
@ 1999-03-08 11:26 John McNally
1999-03-31 19:45 ` John McNally
0 siblings, 1 reply; 10+ messages in thread
From: John McNally @ 1999-03-08 11:26 UTC (permalink / raw)
To: cygwin
I am running cygwin b20.1 with win95 on a 486. I installed the version
of egcs1.1.1 for cygwin b20.
When trying to run g77 (or gcc) I get
This program cannot be run in DOS mode.
Other b20 utils like "ls" and "du" work. I did not check b20 version of
gcc before overlaying egcs version. I have looked in the cygwin mailing
list archives and didn't find anything. And I'm not sure it would be
discussed wrt egcs.
Has anyone else reported this problem? This is the sort of error
message associated with trying to run a windows program from a DOS box,
which is not what I think I'm doing. I don't know much about this.
Just trying to run g77 and b19 version tends to freeze up occasionally.
Thought I'd try an update. B19 still works thankfully.
--
John McNally
Graduate Student, UCLA
Graduate Student Researcher,
UC-Davis/LLNL
P.O. Box 808, L-543
Livermore, CA 94550
voice: (925) 424-5113
FAX: (925) 424-5114
e-mail: mcnally@tempest.engr.ucdavis.edu
--
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^ permalink raw reply [flat|nested] 10+ messages in thread
end of thread, other threads:[~1999-03-31 19:45 UTC | newest]
Thread overview: 10+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
1999-03-08 16:55 problem with cygwin version of egcs Earnie Boyd
[not found] ` < 19990309005620.2525.rocketmail@send102.yahoomail.com >
1999-03-08 17:07 ` DJ Delorie
1999-03-31 19:45 ` DJ Delorie
1999-03-31 19:45 ` Earnie Boyd
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1999-03-08 11:36 Earnie Boyd
[not found] ` < 19990308193738.13807.rocketmail@send102.yahoomail.com >
1999-03-08 12:06 ` DJ Delorie
1999-03-31 19:45 ` DJ Delorie
1999-03-31 19:45 ` Earnie Boyd
1999-03-08 11:26 John McNally
1999-03-31 19:45 ` John McNally
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