[parisc-linux] Assembly Language Changes

[parisc-linux] Assembly Language Changes

[Philipp Rumpf]

Hello,
over the last few days or so, I have been trying to get glibc to build and
work for a Linux/PA-RISC target.  I came to believe it would be simpler to
change certain aspects of the assembly language used than to keep working
around them:

 - Labels should always use ':'
 - mnemonics in the first column should be interpreted normally.
 - register names should always start with '%', not be specified by an
   integer
 - where pa2.0 and pa1.1 differ in opcode names aso, the pa2.0 version
   should be used ("b,l" rather than "bl")
 - ';' should be used rather than '!' to separate multiple statements
   on the same line
 - possibly there should be a line comment character to replace ';' ?

The advantages to changing the assembly dialect we use are that using cpp
to pre-process assembly instructions becomes a lot simpler (glibc makes
heavy use of this);  the assembly language looks more similar to those
used for other architectures that run Linux;  there is no difference
between the pa1.1 and pa2.0 versions.

The disadvantage, obviously, is that we would need to keep separate
binaries around to compile HP/UX assembly source;  also, the assembly
files used by the kernel would need to be converted (and probably get
readable to more people in the process).

The actual work to implement the changes should be pretty low, and I'm
more than willing to do it (and actually already implemented the most
important (to me) changes).

	Philipp Rumpf

Re: [parisc-linux] Assembly Language Changes

[Sam Creasey]

On Sun, 12 Mar 2000, Philipp Rumpf wrote:

> Hello,
> over the last few days or so, I have been trying to get glibc to build and
> work for a Linux/PA-RISC target.  I came to believe it would be simpler to
> change certain aspects of the assembly language used than to keep working
> around them:

At least in the ELF toolchain (which, I think we did change the kernel
over to, didn't we?)  I've already begun freely banging the assembler
syntax into a more gas-like format...   

> The advantages to changing the assembly dialect we use are that using cpp
> to pre-process assembly instructions becomes a lot simpler (glibc makes
> heavy use of this);  the assembly language looks more similar to those
> used for other architectures that run Linux;  there is no difference
> between the pa1.1 and pa2.0 versions.

Agreed.  The original workarounds in the kernel were rather hideous, and
prevented us fron doing quite a few useful things.  (initcalls, anybody?)

Maximum software build support good.

> The disadvantage, obviously, is that we would need to keep separate
> binaries around to compile HP/UX assembly source;  also, the assembly
> files used by the kernel would need to be converted (and probably get
> readable to more people in the process).

Hmph...  I'm not sure how many people working on the port hold a deep
value in the ability to recompile HP/UX apps (or, in this case,
reassemble).  Just run the damn HP assembler if you feel a deep need to
run HP programs under the linux kernel (imho).

-- Sam

Re: [parisc-linux] Assembly Language Changes

[Philipp Rumpf]

> > over the last few days or so, I have been trying to get glibc to build and
> > work for a Linux/PA-RISC target.  I came to believe it would be simpler to
> > change certain aspects of the assembly language used than to keep working
> > around them:
> 
> At least in the ELF toolchain (which, I think we did change the kernel
> over to, didn't we?)  I've already begun freely banging the assembler
> syntax into a more gas-like format...   

nod.  I've got binutils, gcc, glibc, linux moved to the new assembly language
here, just waiting for everyone to have a chance to comment before committing.

> > The disadvantage, obviously, is that we would need to keep separate
> > binaries around to compile HP/UX assembly source;  also, the assembly
> > files used by the kernel would need to be converted (and probably get
> > readable to more people in the process).
> 
> Hmph...  I'm not sure how many people working on the port hold a deep
> value in the ability to recompile HP/UX apps (or, in this case,
> reassemble).  Just run the damn HP assembler if you feel a deep need to
> run HP programs under the linux kernel (imho).

it's a 10-line perl script to convert, so I tend to agree with dropping the
HP syntax completely.

	Philipp

Re: [parisc-linux] Assembly Language Changes

[Philipp Rumpf]

I haven't received any negative comments about the proposed changes yet,
and think the following changes should become effective soon:

>  - Labels should always use ':'
>  - mnemonics in the first column should be interpreted normally.
>  - register names should always start with '%', not be specified by an
>    integer
>  - ';' should be used rather than '!' to separate multiple statements
>    on the same line
- '!' replaces ';' as the line comment character

I don't think a line comment character should be necessary for new code -
C comments (thats /* comment */, not // comment\n) work fine.

So, still no objections ?

	Philipp Rumpf