.arch directive.
The following processor names are recognized:
21064,
21064a,
21066,
21068,
21164,
21164a,
21164pc,
21264,
21264a,
21264b,
ev4,
ev5,
lca45,
ev5,
ev56,
pca56,
ev6,
ev67,
ev68.
The special name all may be used to allow the assembler to accept
instructions valid for any Alpha processor.
In order to support existing practice in OSF/1 with respect to .arch,
and existing practice within MILO (the Linux ARC bootloader), the
numbered processor names (e.g. 21064) enable the processor-specific PALcode
instructions, while the “electro-vlasic” names (e.g. ev4) do not.
.mdebug encapsulation for
stabs directives and procedure descriptors. The default is to automatically
enable .mdebug when the first stabs directive is seen.
.bss,
while smaller symbols are placed in .sbss.