Re: A20 Gate enable sequence (setup.S)
In article <[EMAIL PROTECTED]>, [EMAIL PROTECTED] (Richard B. Johnson) writes: > On Sun, 15 Oct 2000, Robert Kaiser wrote: > >> > The AMD/Elan box snoops for the sequence sent to the keyboard >> > controller to enable A<20>. >> > Robert Kaiser didn't write this. I did. And yes. It makes no difference > about the 'board' it's in the chip. Well, if it is in the chip, then what ever is in there doesn't work properly: I have seen several different AMD Elan boards that failed to boot Linux. Adding the "fast A20 enable" via port 0x92 to setup.S fixed the problem in all cases. >> > The AMD/Elan chip also comes to life after a hardware reset with >> > A<20> enabled. So, if you don't turn it OFF, there won't be any >> > problem during the protected-mode transition. >> >> Sure, but whether you CAN leave it on depends on the board's BIOS. >> Some of them are "smart" and won't let you configure the initial >> A20 state. Adding the port 0x92 method to setup.S as I'm suggesting >> would be safe in all cases (assuming it won't break anything else). >> > > Many who use Linux in embeded systems write their own BIOS as I > have done. Then you don't have to pay $10/box you ship to a BIOS > vendor who ripped off all the code anyway. I hope you are not seriously suggesting that everyone who uses Linux in embedded systems should be prepared to write their own BIOS. Of course it's nice if you don't have to pay BIOS royalties, but in my experience, people who have a high enough volume so that writing their own BIOS would make sense tend to go for a different architecture (PPC, ARM, MIPS, SH) in the first place. (BTW, is your BIOS under GPL perchance ?) > FYI, the code that was submitted can't possibly work (it was backwards). > If it made your board 'work' there is something else broken. Yep, my fault: The code _did_ work in a 2.2.x kernel, but I applied the change to the latest 2.4 kernel, not realizing that the assembly syntax had been changed in the meantime. I should have at least tested it. See below for a corrected version. This time I've tested it: the unmodified kernel fails to boot on a JUMPtec DIMM-PC (with AMD Elan SC410), the patched kernel does boot. Some may argue that simply writing 0x02 to port 0x92 would do the job and they may well be right (it does work that way on the DIMM-PC). My suggested code makes sure to keep bits #7-#2 unmodified and it always clears bit #0 (CPU reset). Call me paranoid, but I think this is worth two extra assembly instructions :-). diff -urN linux-2.4.0-test8/arch/i386/boot/setup.S linux/arch/i386/boot/setup.S --- linux-2.4.0-test8/arch/i386/boot/setup.SWed Jul 19 07:00:33 2000 +++ linux/arch/i386/boot/setup.SMon Oct 16 15:27:48 2000 @@ -631,6 +631,16 @@ # appropriate # that was painless, now we enable a20 + +# enable the "fast" A20 gate + + inb $0x92, %al + orb $0x02, %al + andb$0xfe, %al + outb%al, $0x92 + +# enable the keyboard controller A20 gate + callempty_8042 movb$0xD1, %al # command write Robert Kaiser email: [EMAIL PROTECTED] SYSGO RTS GmbH Am Pfaffenstein 14phone: (49) 6136 9948-762 D-55270 Klein-Winternheim / Germany fax: (49) 6136 9948-10 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] Please read the FAQ at http://www.tux.org/lkml/
Re: A20 Gate enable sequence (setup.S)
Richard B. Johnson wrote.. > Robert Kaiser didn't write this. I did. You and a few hundred other embedded systems programmers. > FYI, the code that was submitted can't possibly work (it was backwards). > If it made your board 'work' there is something else broken. What do you mean backwards? The only broken part I see is that unlike the same routine in 2.2, this one doesn't preserve the other bits. (Which the 2.4 code really should be doing or very strange things may happen on certain hardware) regards, Dave. -- | Dave Jones <[EMAIL PROTECTED]> http://www.suse.de/~davej | SuSE Labs - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] Please read the FAQ at http://www.tux.org/lkml/
Re: A20 Gate enable sequence (setup.S)
On Sun, 15 Oct 2000, Robert Kaiser wrote: > > The AMD/Elan box snoops for the sequence sent to the keyboard > > controller to enable A<20>. > Robert Kaiser didn't write this. I did. And yes. It makes no difference about the 'board' it's in the chip. > Are you sure this is true of all boards using the AMD Elan ? > So far, I've dealt with three different AMD Elan boards and only > one of them (Jumptec DIMM-PC) seemed to have this feature. But even > on that one, Linux wouldn't boot out of the box because of A20 problems > (you had to reset the keyboard controller to make it work). > The keyboard controller is in a seperate Super I/O chip. You can 'pretend' to go through the motions, but there is no connection whatsoever (no pin, no trace) to connect the keyboard output bit to A<20> enable. It's all done by the AMD internal snoop. So if you write the right stuff to the right port, the bit is enabled. > > However, it also respects the port > > 0x92 control. > > The i386EX has port 0x92 built in (it does not have a built-in > keyboard controller ..), so port 0x92 should work on all 386EX > boards whereas the keyboard controller sequence may or may not work. > > > > The AMD/Elan chip also comes to life after a hardware reset with > > A<20> enabled. So, if you don't turn it OFF, there won't be any > > problem during the protected-mode transition. > > Sure, but whether you CAN leave it on depends on the board's BIOS. > Some of them are "smart" and won't let you configure the initial > A20 state. Adding the port 0x92 method to setup.S as I'm suggesting > would be safe in all cases (assuming it won't break anything else). > Many who use Linux in embeded systems write their own BIOS as I have done. Then you don't have to pay $10/box you ship to a BIOS vendor who ripped off all the code anyway. FYI, the code that was submitted can't possibly work (it was backwards). If it made your board 'work' there is something else broken. Cheers, Dick Johnson Penguin : Linux version 2.2.17 on an i686 machine (801.18 BogoMips). "Memory is like gasoline. You use it up when you are running. Of course you get it all back when you reboot..."; Actual explanation obtained from the Micro$oft help desk. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] Please read the FAQ at http://www.tux.org/lkml/
Re: A20 Gate enable sequence (setup.S)
> The AMD/Elan box snoops for the sequence sent to the keyboard > controller to enable A<20>. Are you sure this is true of all boards using the AMD Elan ? So far, I've dealt with three different AMD Elan boards and only one of them (Jumptec DIMM-PC) seemed to have this feature. But even on that one, Linux wouldn't boot out of the box because of A20 problems (you had to reset the keyboard controller to make it work). > However, it also respects the port > 0x92 control. The i386EX has port 0x92 built in (it does not have a built-in keyboard controller ..), so port 0x92 should work on all 386EX boards whereas the keyboard controller sequence may or may not work. > The AMD/Elan chip also comes to life after a hardware reset with > A<20> enabled. So, if you don't turn it OFF, there won't be any > problem during the protected-mode transition. Sure, but whether you CAN leave it on depends on the board's BIOS. Some of them are "smart" and won't let you configure the initial A20 state. Adding the port 0x92 method to setup.S as I'm suggesting would be safe in all cases (assuming it won't break anything else). Rob Robert Kaiser email: [EMAIL PROTECTED] SYSGO RTS GmbH Am Pfaffenstein 14http://www.elinos.com D-55270 Klein-Winternheim / Germany http://www.sysgo.de - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] Please read the FAQ at http://www.tux.org/lkml/
Re: A20 Gate enable sequence (setup.S)
On Fri, 13 Oct 2000, Albert Cranford wrote: > Robert Kaiser wrote: > > > > On Fre, 13 Okt 2000 you wrote: > > > > Some boards (especially in the embedded PC area) implement only the > > > > latter method (some don't even _have_ a keyboard controller). > > > > With these boards, Linux fails to boot. > > > > > > Try the current 2.2.18pre. This has fast A20 too and I suspect will boot > > > on your box. Its had no problems on 2.2.18pre reported against it so far. I've > > > not done a 2.4 test patch but yours seems to be the sam ething > > > > Thanks for the hint, I hadn't checked that version > > > > > > > > AMD ELAN ? > > > > Actually several different boards, some using AMD ELAN, some 386 EX. > > > > Rob > > > > Here is a wroking 2.4.0 version, which is from Randy Dunlaps patch. > Later, > Albert Thanks Albert! Actually I was aware of this patch (saw it in the archives), but, it seemed to me that this patch hadn't made it into the standard kernel (2.4.0-test8 didn't have it), so I thought I might bring up this issue once more. I just learned from Alan, that he added it in 2.2.18pre, so I'll test that one and if it works, I'll be all happy :-). Rob Robert Kaiser email: [EMAIL PROTECTED] SYSGO RTS GmbH Am Pfaffenstein 14 http://www.elinos.com D-55270 Klein-Winternheim / Germany http://www.sysgo.de - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] Please read the FAQ at http://www.tux.org/lkml/
Re: A20 Gate enable sequence (setup.S)
On Fri, 13 Oct 2000, Alan Cox wrote: > > Some boards (especially in the embedded PC area) implement only the > > latter method (some don't even _have_ a keyboard controller). > > With these boards, Linux fails to boot. > > Try the current 2.2.18pre. This has fast A20 too and I suspect will boot > on your box. Its had no problems on 2.2.18pre reported against it so far. I've > not done a 2.4 test patch but yours seems to be the sam ething > > AMD ELAN ? The AMD/Elan box snoops for the sequence sent to the keyboard controller to enable A<20>. However, it also respects the port 0x92 control. Linux-2.2.17 doesn't have the 0x92 control so it must have been added recently. The AMD/Elan chip also comes to life after a hardware reset with A<20> enabled. So, if you don't turn it OFF, there won't be any problem during the protected-mode transition. Cheers, Dick Johnson Penguin : Linux version 2.2.17 on an i686 machine (801.18 BogoMips). "Memory is like gasoline. You use it up when you are running. Of course you get it all back when you reboot..."; Actual explanation obtained from the Micro$oft help desk. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] Please read the FAQ at http://www.tux.org/lkml/
Re: A20 Gate enable sequence (setup.S)
Robert Kaiser wrote: > > On Fre, 13 Okt 2000 you wrote: > > > Some boards (especially in the embedded PC area) implement only the > > > latter method (some don't even _have_ a keyboard controller). > > > With these boards, Linux fails to boot. > > > > Try the current 2.2.18pre. This has fast A20 too and I suspect will boot > > on your box. Its had no problems on 2.2.18pre reported against it so far. I've > > not done a 2.4 test patch but yours seems to be the sam ething > > Thanks for the hint, I hadn't checked that version > > > > > AMD ELAN ? > > Actually several different boards, some using AMD ELAN, some 386 EX. > > Rob > > > Robert Kaiser email: [EMAIL PROTECTED] > SYSGO RTS GmbH > Am Pfaffenstein 14phone: (49) 6136 9948-762 > D-55270 Klein-Winternheim / Germany fax: (49) 6136 9948-10 > - > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to [EMAIL PROTECTED] > Please read the FAQ at http://www.tux.org/lkml/ Here is a wroking 2.4.0 version, which is from Randy Dunlaps patch. Later, Albert --- linux-2.4.0/arch/i386/boot/setup.S.orig Mon Jul 17 20:32:00 2000 +++ linux/arch/i386/boot/setup.SMon Jul 17 20:35:10 2000 @@ -640,6 +640,8 @@ movb$0xDF, %al # A20 on outb%al, $0x60 callempty_8042 + movb$0x2, %al # Gate A20 functionality is achieved + outb%al, $0x92 # via port 0x92, bit 1. # wait until a20 really *is* enabled; it can take a fair amount of # time on certain systems; Toshiba Tecras are known to have this --- From: "Dunlap, Randy" <[EMAIL PROTECTED]> To: "'Agust Karlsson'" <[EMAIL PROTECTED]>, "'[EMAIL PROTECTED]'" <[EMAIL PROTECTED]>, "'[EMAIL PROTECTED]'" <[EMAIL PROTECTED]> Subject: RE: A20 gate control question. Date: Mon, 17 Jul 2000 09:46:17 -0700 MIME-Version: 1.0 X-Mailer: Internet Mail Service (5.5.2448.0) Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 8BIT Sender: [EMAIL PROTECTED] Precedence: bulk X-Loop: [EMAIL PROTECTED] X-Mozilla-Status: 8011 X-Mozilla-Status2: X-UIDL: a4b217d6c05a8b4bb97c23a40bca51e7 > Hi. Jesse Off ([EMAIL PROTECTED]) posted a patch to do this on Oct. 26, 1999. His patch needs to be added to setup.S IMO, along with the current gating of A20. The company I work for, NewMonics, does a lot of work on embedded systems and we've recently ported our product (a lightweight realtime Java virtual machine) to Linux. On some of the embedded systems/PLC's we work with (specifically, those based on the AMD Elan SC310 and SC300 386 microcontrollers) Linux fails to boot because the keyboard controller is not there to set the A20 bit. These machines are headless, keyboardless, and diskless (except for a small PCMCIA flash card). With the following patch, we were able to get our virtual machine running on Linux under this hardware via a serial port console. --- setup.S Mon Aug 9 12:04:38 1999 +++ setup.S.patched Tue Oct 26 10:50:36 1999 @@ -553,6 +553,15 @@ out #0x60,al callempty_8042 +! The AMD 386 Elan SC300 and SC310 microcontrollers which +! are used in some embedded systems don't have +! a keyboard controller; we have to do things different on +! these chips. Jesse Off, NewMonics, Inc. <[EMAIL PROTECTED]> + + mov al,#0x2 ! GATEA20 functionality is acheived + out #0x92, al ! via port 0x92, bit 1. + + ! wait until a20 really *is* enabled; it can take a fair amount of ! time on certain systems; Toshiba Tecras are known to have this ! problem. The memory location used here is the int 0x1f vector, - This applies to newer Intel systems also. I asked internally if port 0x92 might have conflicts with other chipsets and the answer I got was "no." Also, from other email on this subject, is there an implication here that the timeout (counter) in "empty_8042" doesn't work (on systems that don't have an 8042 controller)? ~Randy ___ |Randy Dunlap Intel Corp., DALSr. SW Engr.| |randy.dunlap.at.intel.com503-696-2055| |NOTE: Any views presented here are mine alone | |and may not represent the views of my employer. | |_| -- Albert Cranford Deerfield Beach FL USA [EMAIL PROTECTED] - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] Please read the FAQ at http://www.tux.org/lkml/
Re: A20 Gate enable sequence (setup.S)
On Fre, 13 Okt 2000 you wrote: > > Some boards (especially in the embedded PC area) implement only the > > latter method (some don't even _have_ a keyboard controller). > > With these boards, Linux fails to boot. > > Try the current 2.2.18pre. This has fast A20 too and I suspect will boot > on your box. Its had no problems on 2.2.18pre reported against it so far. I've > not done a 2.4 test patch but yours seems to be the sam ething Thanks for the hint, I hadn't checked that version > > AMD ELAN ? Actually several different boards, some using AMD ELAN, some 386 EX. Rob Robert Kaiser email: [EMAIL PROTECTED] SYSGO RTS GmbH Am Pfaffenstein 14phone: (49) 6136 9948-762 D-55270 Klein-Winternheim / Germany fax: (49) 6136 9948-10 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] Please read the FAQ at http://www.tux.org/lkml/
Re: A20 Gate enable sequence (setup.S)
On Fri, 13 Oct 2000, Robert Kaiser wrote: > + > +# enable the "fast" A20 gate > + > + in al,#0x92 > + or al,#2 > + and al,#0xfe > + out #0x92,al > + this is not a valid AT assembler but looks like some ancient Intel syntax. Linux kernel is written using AT syntax (thanks to Chris Noe who did the translation). Please rewrite it and re-submit for everyone to test, e.g. in should be inb, the arguments are in the wrong order etc etc. Regards, Tigran - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] Please read the FAQ at http://www.tux.org/lkml/
Re: A20 Gate enable sequence (setup.S)
> Some boards (especially in the embedded PC area) implement only the > latter method (some don't even _have_ a keyboard controller). > With these boards, Linux fails to boot. Try the current 2.2.18pre. This has fast A20 too and I suspect will boot on your box. Its had no problems on 2.2.18pre reported against it so far. I've not done a 2.4 test patch but yours seems to be the sam ething AMD ELAN ? - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] Please read the FAQ at http://www.tux.org/lkml/
Re: A20 Gate enable sequence (setup.S)
Some boards (especially in the embedded PC area) implement only the latter method (some don't even _have_ a keyboard controller). With these boards, Linux fails to boot. Try the current 2.2.18pre. This has fast A20 too and I suspect will boot on your box. Its had no problems on 2.2.18pre reported against it so far. I've not done a 2.4 test patch but yours seems to be the sam ething AMD ELAN ? - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] Please read the FAQ at http://www.tux.org/lkml/
Re: A20 Gate enable sequence (setup.S)
On Fri, 13 Oct 2000, Robert Kaiser wrote: + +# enable the "fast" A20 gate + + in al,#0x92 + or al,#2 + and al,#0xfe + out #0x92,al + this is not a valid ATT assembler but looks like some ancient Intel syntax. Linux kernel is written using ATT syntax (thanks to Chris Noe who did the translation). Please rewrite it and re-submit for everyone to test, e.g. in should be inb, the arguments are in the wrong order etc etc. Regards, Tigran - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] Please read the FAQ at http://www.tux.org/lkml/
Re: A20 Gate enable sequence (setup.S)
On Fre, 13 Okt 2000 you wrote: Some boards (especially in the embedded PC area) implement only the latter method (some don't even _have_ a keyboard controller). With these boards, Linux fails to boot. Try the current 2.2.18pre. This has fast A20 too and I suspect will boot on your box. Its had no problems on 2.2.18pre reported against it so far. I've not done a 2.4 test patch but yours seems to be the sam ething Thanks for the hint, I hadn't checked that version AMD ELAN ? Actually several different boards, some using AMD ELAN, some 386 EX. Rob Robert Kaiser email: [EMAIL PROTECTED] SYSGO RTS GmbH Am Pfaffenstein 14phone: (49) 6136 9948-762 D-55270 Klein-Winternheim / Germany fax: (49) 6136 9948-10 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] Please read the FAQ at http://www.tux.org/lkml/
