lkml.org 
[lkml]   [2002]   [Jan]   [12]   [last100]   RSS-feed
Views: [more markup]  [less markup]  [headers]  [forward] 
 
Messages in this thread
Complete thread (EXPERIMENTAL)
/
DateSat, 12 Jan 2002 10:00:17 +0100 (CET)
Fromwilly tarreau <>
SubjectRe: [Q] Looking for an emulation for CMOV* instructions.
Digg This
Gee, when was the last time Intel removed something from the instruction set? An old 80286 instruction
comes to mind, but that was a super-CISC mess that
was really specific to the implementation. Anything really useful that was ever removed?

well, the 8088/8086 supported the POP CS instruction which was used by a virus and 80186/80286 broke this virus (which was rewritten anyway).

The undocumented loadall instruction changes from
CPU to CPU, and the IBTS/XBTS bit string manipulation instructions appeared in Step A 386 and disappeared later. The Step A 486 reused their opcodes for CMPXCHG and it changed just after in Step B.

This are very rare cases, but at least some
developpers could have based their work on the
existence of IBTS/XBTS but it disappeared.

Anyway, I cannot imagine that they could break
compatibility by removing CMOV !

Regards,
Willy


___________________________________________________________
Do You Yahoo!? -- Une adresse @yahoo.fr gratuite et en français !
Yahoo! Courrier : http://courrier.yahoo.fr
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

\
ISP Services
Valid XHTML 1.0!\ /
Valid CSS! Last update: 2005-03-22 12:15    [W:0.319 / U:0.020 seconds]
©2003-2005 Jasper Spaans