* [harmon@metronet.com: GNU GAS i386 16 bit]
@ 1994-08-24 21:16 Ian Lance Taylor
1994-08-25 5:56 ` Michael Meissner
1994-08-25 6:28 ` Arthur Kreitman
0 siblings, 2 replies; 6+ messages in thread
From: Ian Lance Taylor @ 1994-08-24 21:16 UTC (permalink / raw)
To: gas2; +Cc: Thomas Harmon
I know as little as possible about the i386, and I certainly know
nothing about the differences between 16 and 32 bit mode. Can anybody
on this list help? I'm sure that nobody at Cygnus plans to add
support for 16 bit mode, unless, of course, we find somebody to pay
for it.
Ian
Date: Wed, 24 Aug 1994 20:27:16 -0500
From: Thomas Harmon <harmon@metronet.com>
To: ian@tweedledumb.cygnus.com
Subject: GNU GAS i386 16 bit
Ian,
My name is Thomas Harmon. I found your E-mail address in the 2.3
version of GNU GAS. Please excuse me for bothering you. I would like to
ask for your opinion on some modifications I would like to make to GAS.
I am working on a major project which requires a cross-platform,
x86 assembler, for both 16 and 32 bit code. That is where my problem lies,
I know GAS does not currently support 16 bit code, but how much effort do
you think it will take to add it? Is this being planned for GAS? If so,
when do you think it will be done? If it looks like I'll need to add 16-bit
support myself, please send me a list of things I'll need to check. I think
I can figure it out from the 2.3 distribution, but I'd like to know about
any special problems that are not immediately obvious.
Thank you for your time.
-----------------------------------------------------------------------------
Thomas Harmon "He's no fun, he fell right over."
harmon@feenix.metronet.com -- Four or Five Crazy Guys
-----------------------------------------------------------------------------
^ permalink raw reply [flat|nested] 6+ messages in thread* [harmon@metronet.com: GNU GAS i386 16 bit]
1994-08-24 21:16 [harmon@metronet.com: GNU GAS i386 16 bit] Ian Lance Taylor
@ 1994-08-25 5:56 ` Michael Meissner
1994-08-25 6:28 ` Arthur Kreitman
1 sibling, 0 replies; 6+ messages in thread
From: Michael Meissner @ 1994-08-25 5:56 UTC (permalink / raw)
To: ian; +Cc: gas2, harmon
| I know as little as possible about the i386, and I certainly know
| nothing about the differences between 16 and 32 bit mode. Can anybody
| on this list help? I'm sure that nobody at Cygnus plans to add
| support for 16 bit mode, unless, of course, we find somebody to pay
| for it.
Adding 16 bit support is probably straight forward (ie, the work isn't
simple, but once you learn your way around the sources, it isn't that
hard). You will probably have to have a global mode bit that says 16
or 32 bit instructions are being generated. Note, some object file
formats (notably ELF) on the 386 don't have relocation types for
16-bit relocations. All in all, it is probably a couple of months of
work.
| Ian
|
| Date: Wed, 24 Aug 1994 20:27:16 -0500
| From: Thomas Harmon <harmon@metronet.com>
| To: ian@tweedledumb.cygnus.com
| Subject: GNU GAS i386 16 bit
|
|
| Ian,
|
| My name is Thomas Harmon. I found your E-mail address in the 2.3
| version of GNU GAS. Please excuse me for bothering you. I would like to
| ask for your opinion on some modifications I would like to make to GAS.
|
| I am working on a major project which requires a cross-platform,
| x86 assembler, for both 16 and 32 bit code. That is where my problem lies,
| I know GAS does not currently support 16 bit code, but how much effort do
| you think it will take to add it? Is this being planned for GAS? If so,
| when do you think it will be done? If it looks like I'll need to add 16-bit
| support myself, please send me a list of things I'll need to check. I think
| I can figure it out from the 2.3 distribution, but I'd like to know about
| any special problems that are not immediately obvious.
|
| Thank you for your time.
|
| -----------------------------------------------------------------------------
| Thomas Harmon "He's no fun, he fell right over."
| harmon@feenix.metronet.com -- Four or Five Crazy Guys
| -----------------------------------------------------------------------------
|
|
|
|
^ permalink raw reply [flat|nested] 6+ messages in thread
* [harmon@metronet.com: GNU GAS i386 16 bit]
1994-08-24 21:16 [harmon@metronet.com: GNU GAS i386 16 bit] Ian Lance Taylor
1994-08-25 5:56 ` Michael Meissner
@ 1994-08-25 6:28 ` Arthur Kreitman
1994-08-25 6:52 ` Michael Meissner
1 sibling, 1 reply; 6+ messages in thread
From: Arthur Kreitman @ 1994-08-25 6:28 UTC (permalink / raw)
To: ian; +Cc: gas2, harmon
I don't think you want to add 16 bit support even if someone pays
you to do it. The real issue is the binary format. For object
modules, the format is something called OMF. The executable program
format is something else. I would guess that adding OMF to gas (and
all that bfd stuff) will take man-years.
From: Ian Lance Taylor <ian@cygnus.com>
Date: Thu, 25 Aug 94 00:16:31 EDT
I know as little as possible about the i386, and I certainly know
nothing about the differences between 16 and 32 bit mode. Can anybody
on this list help? I'm sure that nobody at Cygnus plans to add
support for 16 bit mode, unless, of course, we find somebody to pay
for it.
Ian
Date: Wed, 24 Aug 1994 20:27:16 -0500
From: Thomas Harmon <harmon@metronet.com>
To: ian@tweedledumb.cygnus.com
Subject: GNU GAS i386 16 bit
Ian,
My name is Thomas Harmon. I found your E-mail address in the 2.3
version of GNU GAS. Please excuse me for bothering you. I would like to
ask for your opinion on some modifications I would like to make to GAS.
I am working on a major project which requires a cross-platform,
x86 assembler, for both 16 and 32 bit code. That is where my problem lies,
I know GAS does not currently support 16 bit code, but how much effort do
you think it will take to add it? Is this being planned for GAS? If so,
when do you think it will be done? If it looks like I'll need to add 16-bit
support myself, please send me a list of things I'll need to check. I think
I can figure it out from the 2.3 distribution, but I'd like to know about
any special problems that are not immediately obvious.
Thank you for your time.
-----------------------------------------------------------------------------
Thomas Harmon "He's no fun, he fell right over."
harmon@feenix.metronet.com -- Four or Five Crazy Guys
-----------------------------------------------------------------------------
^ permalink raw reply [flat|nested] 6+ messages in thread
* [harmon@metronet.com: GNU GAS i386 16 bit]
1994-08-25 6:28 ` Arthur Kreitman
@ 1994-08-25 6:52 ` Michael Meissner
1994-08-25 7:53 ` Arthur Kreitman
1994-08-25 8:03 ` DJ Delorie
0 siblings, 2 replies; 6+ messages in thread
From: Michael Meissner @ 1994-08-25 6:52 UTC (permalink / raw)
To: artk; +Cc: ian, gas2, harmon
|
| I don't think you want to add 16 bit support even if someone pays
| you to do it. The real issue is the binary format. For object
| modules, the format is something called OMF. The executable program
| format is something else. I would guess that adding OMF to gas (and
| all that bfd stuff) will take man-years.
If somebody pays reasonably to get the work done, I would certainly
consider doing it, providing I wasn't employed at the time. Others
would too. I'm sure Cygnus would do it if the cost was enough.
Adding a new object format can certainly be done. It depends on what
trickyness is in OMF. If it doesn't require things that aren't
already in BFD (such as shared library support), it would be
straigtforward. That's what BFD is for in the first place. I also
seem to recall there are gas ports to OMF floating around (pre-BFD).
You might ask DJ Delorie (dj@ctron.com), if he isn't on the mailing
list for thoughts, since he is closer to the MSDOS world than most of
us UNIX-oids/GNU-oids are.
|
|
| From: Ian Lance Taylor <ian@cygnus.com>
| Date: Thu, 25 Aug 94 00:16:31 EDT
|
| I know as little as possible about the i386, and I certainly know
| nothing about the differences between 16 and 32 bit mode. Can anybody
| on this list help? I'm sure that nobody at Cygnus plans to add
| support for 16 bit mode, unless, of course, we find somebody to pay
| for it.
|
| Ian
|
| Date: Wed, 24 Aug 1994 20:27:16 -0500
| From: Thomas Harmon <harmon@metronet.com>
| To: ian@tweedledumb.cygnus.com
| Subject: GNU GAS i386 16 bit
|
|
| Ian,
|
| My name is Thomas Harmon. I found your E-mail address in the 2.3
| version of GNU GAS. Please excuse me for bothering you. I would like to
| ask for your opinion on some modifications I would like to make to GAS.
|
| I am working on a major project which requires a cross-platform,
| x86 assembler, for both 16 and 32 bit code. That is where my problem lies,
| I know GAS does not currently support 16 bit code, but how much effort do
| you think it will take to add it? Is this being planned for GAS? If so,
| when do you think it will be done? If it looks like I'll need to add 16-bit
| support myself, please send me a list of things I'll need to check. I think
| I can figure it out from the 2.3 distribution, but I'd like to know about
| any special problems that are not immediately obvious.
|
| Thank you for your time.
|
| -----------------------------------------------------------------------------
| Thomas Harmon "He's no fun, he fell right over."
| harmon@feenix.metronet.com -- Four or Five Crazy Guys
| -----------------------------------------------------------------------------
|
|
|
|
^ permalink raw reply [flat|nested] 6+ messages in thread
* [harmon@metronet.com: GNU GAS i386 16 bit]
1994-08-25 6:52 ` Michael Meissner
@ 1994-08-25 7:53 ` Arthur Kreitman
1994-08-25 8:03 ` DJ Delorie
1 sibling, 0 replies; 6+ messages in thread
From: Arthur Kreitman @ 1994-08-25 7:53 UTC (permalink / raw)
To: meissner; +Cc: ian, gas2, harmon
The other issue is the future of OMF and 16 bit x86. Microsoft's 32 bit
compilers all pump out a coff'ish object format. And with new product
releases, even Microsoft won't be supporting OMF. Its difficult to see
why anyone would want to pay for work that will be useless by the time
its completed.,
From: Michael Meissner <meissner@osf.org>
Date: Thu, 25 Aug 94 09:52:18 -0400
References: < 9408250416.AA13401@tweedledumb.cygnus.com >
< 9408251313.AA19072@Congruent.COM >
|
| I don't think you want to add 16 bit support even if someone pays
| you to do it. The real issue is the binary format. For object
| modules, the format is something called OMF. The executable program
| format is something else. I would guess that adding OMF to gas (and
| all that bfd stuff) will take man-years.
If somebody pays reasonably to get the work done, I would certainly
consider doing it, providing I wasn't employed at the time. Others
would too. I'm sure Cygnus would do it if the cost was enough.
Adding a new object format can certainly be done. It depends on what
trickyness is in OMF. If it doesn't require things that aren't
already in BFD (such as shared library support), it would be
straigtforward. That's what BFD is for in the first place. I also
seem to recall there are gas ports to OMF floating around (pre-BFD).
You might ask DJ Delorie (dj@ctron.com), if he isn't on the mailing
list for thoughts, since he is closer to the MSDOS world than most of
us UNIX-oids/GNU-oids are.
|
|
| From: Ian Lance Taylor <ian@cygnus.com>
| Date: Thu, 25 Aug 94 00:16:31 EDT
|
| I know as little as possible about the i386, and I certainly know
| nothing about the differences between 16 and 32 bit mode. Can anybody
| on this list help? I'm sure that nobody at Cygnus plans to add
| support for 16 bit mode, unless, of course, we find somebody to pay
| for it.
|
| Ian
|
| Date: Wed, 24 Aug 1994 20:27:16 -0500
| From: Thomas Harmon <harmon@metronet.com>
| To: ian@tweedledumb.cygnus.com
| Subject: GNU GAS i386 16 bit
|
|
| Ian,
|
| My name is Thomas Harmon. I found your E-mail address in the 2.3
| version of GNU GAS. Please excuse me for bothering you. I would like to
| ask for your opinion on some modifications I would like to make to GAS.
|
| I am working on a major project which requires a cross-platform,
| x86 assembler, for both 16 and 32 bit code. That is where my problem lies,
| I know GAS does not currently support 16 bit code, but how much effort do
| you think it will take to add it? Is this being planned for GAS? If so,
| when do you think it will be done? If it looks like I'll need to add 16-bit
| support myself, please send me a list of things I'll need to check. I think
| I can figure it out from the 2.3 distribution, but I'd like to know about
| any special problems that are not immediately obvious.
|
| Thank you for your time.
|
| -----------------------------------------------------------------------------
| Thomas Harmon "He's no fun, he fell right over."
| harmon@feenix.metronet.com -- Four or Five Crazy Guys
| -----------------------------------------------------------------------------
|
|
|
|
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [harmon@metronet.com: GNU GAS i386 16 bit]
1994-08-25 6:52 ` Michael Meissner
1994-08-25 7:53 ` Arthur Kreitman
@ 1994-08-25 8:03 ` DJ Delorie
1 sibling, 0 replies; 6+ messages in thread
From: DJ Delorie @ 1994-08-25 8:03 UTC (permalink / raw)
To: meissner; +Cc: artk, ian, gas2, harmon
> Adding a new object format can certainly be done. It depends on what
> trickyness is in OMF. If it doesn't require things that aren't
> already in BFD (such as shared library support), it would be
> straigtforward. That's what BFD is for in the first place. I also
> seem to recall there are gas ports to OMF floating around (pre-BFD).
> You might ask DJ Delorie (dj@ctron.com), if he isn't on the mailing
> list for thoughts, since he is closer to the MSDOS world than most of
> us UNIX-oids/GNU-oids are.
The OMF format is different from any Unix format, but EMX (gcc for
os/2) produces 32-bit OMF so it *can* be done. I don't know what the
changes entail, though.
The biggest difference when dealing ith DOS OMF and 16-bit assembler
is something that's come up before - segments. DOS has lots of them,
and gcc et al just don't support them very well. With OMF and BFD,
you could treat segments like sections, so you could probably get
something that worked without having to re-engineer the BFD interface
itself.
Making gas support intel mixed assembler is a different story. Little
of the i386 code will be reusable, since 16-bit opcodes have different
formats than the 32-bit ones (might as well be a whole new CPU).
Also, you'll need to keep track of operand and address size overrides,
which gas does for the i386 but will need to be extended. Also, the
concept of default segments and use directives will be a new
experience for gas.
I think someone who has implemented support for a processor from
scratch should be able to add 16/32 OMF support without undue
difficulty, though. Teaching gcc about it is a different story,
however.
gnuoids?
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~1994-08-25 8:03 UTC | newest]
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1994-08-24 21:16 [harmon@metronet.com: GNU GAS i386 16 bit] Ian Lance Taylor
1994-08-25 5:56 ` Michael Meissner
1994-08-25 6:28 ` Arthur Kreitman
1994-08-25 6:52 ` Michael Meissner
1994-08-25 7:53 ` Arthur Kreitman
1994-08-25 8:03 ` DJ Delorie
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