The on-board serial port implemented in the SC400 silicon has a bug which
makes it behave slightly different than a 16550A. I have patched serial.c
and it works fine, but I doubt that my patch is general pupose enough for
the mainline source tree. The actual bug has to do with a one clock cycle
delay in the assertion of LSR I think. Hope this helps.
diff serial.c /usr/src/pristine-2.2.5/drivers/char/serial.c
69,70d68
<
<
613c611
< printk("status = %x...", status);
---
> printk("status = %x...", status);
621d618
<
653c650
< int status, iir;
---
> int status;
676d672
< iir = serial_in(info, UART_IIR);
679c675
< printk("status = %x iir=%x...\n", status,iid);
---
> printk("status = %x...", status);
681,683d676
< status = serial_inp(info, UART_LSR);
<
< //#endif
687,688c680
<
< if ((status & UART_LSR_THRE) || (iir & UART_IIR_THRI))
---
> if (status & UART_LSR_THRE)
2933d2924
<
2935d2925
<
[awaddell@freebird char]$
-----Original Message-----
From: Oleg Perelet [mailto:[EMAIL PROTECTED]]
Sent: Wednesday, May 12, 1999 10:26 AM
To: Chris Wyszkowski; 'Oleg Perelet'
Cc: [EMAIL PROTECTED]
Subject: RE: Running directly from ROM?
Chris, I wrote pretty dumm AMD 22/23 register setup (why everybody is
scared of 256 extra registers to load:) and protected mode switcher.
If you have 4MB(or 8 or 16...) linear memory PCMCIA card and tools
to dump image on it, I can send you boot image. The only thing that
I'm not doing right now - DRAM type detection, mainly because our
(home made) board has DRAM soldered on. AMD uses different DRAM
SIMMS on their boards, but there is AMD asm code to do this detect.
Also does anybody knows what is the problem with on chip AMD serial? If
I use SIO com1 everything is fine, if I switch on on chip serial
(1st serial connector) serial is pretty screwy (I have the same
problems with qnx - so it's not about linux)
At 12:50 PM 5/12/99 -0400, Chris Wyszkowski wrote:
>Oleg,
>
>I have SC410 HW prototyped along the lines you are discussing. I am now
>looking to see what I need in terms of a loader (I don't want a PC stype
BIOS.)
> Can you tell me what your solution was? I was thinking a MILO style
loader
>would be best, but it may be overkill.
>
>I have been watching this mailing list for some time and this seems to be a
>recurring barrier, anyone have some definitive ROMable loaders available
for
>the AMD Elan family that allow boot from flash?
>
>Chris Wyszkowski
>
>On Wednesday, May 12, 1999 12:39 PM, Oleg Perelet [SMTP:[EMAIL PROTECTED]]
>wrote:
>> You can look at AMD Elan CPU's very need and flexible architecture,
>> with 4MB Flash/ROM, 8MB of DRAM and simple network chip you can
>> build pretty inexpensive system (<$400 in low quantities).
>> And there is no problem running linux in there. (I run 2.2.3).
>>
>>
>> Oleg.
>>
>>
>> At 12:23 PM 5/12/99 +1000, you wrote:
>> >Hi Folks,
>> >
>> >I'm currently investigating options for a minimal-cost x386 based
diskless
>> >embedded controller running a stripped-down Linux kernel for a
reasonably
>> >simple embedded TCP/IP application. I'm very interested in opinions or
>> >experience anyone could offer.
>> >
>> >My choice of x386 is to allow easy hardware & software prototyping on
>> >desktop
>> >PC's and off-the-shelf embedded biscuit-PC-like boards. Ultimately, I'd
like
>> >to
>> >build a tiny BIOS-less system with traditional (i.e. non-IDE)
flash/eprom
>> >memory and minimal RAM. Since the Linux kernel has a larger footprint
than
>> >traditional embedded OS's, it would be nice to run it directly from ROM
with
>> >a ROM-based root filesystem. I'd prefer not to simply copy the kernel
into
>> >RAM
>> >or use an "initrd" RAM-disk for root filesystem stuff which is all
>> >essentially
>> >read-only. Demonstrating that Linux can run embedded with very little
RAM is
>> >one of the goals here, even at the expense of slightly more ROM.
>> >
>> >My guess is that much of the specifics here can be handled by a
ROM-based
>> >bootloader which sets up the x386 MMU to effectively "load" the kernel,
and
>> >from then on everything is much like running in a desktop box, albeit a
>> >severely stripped one. Does anyone know of an existing bootloader that
can
>> >perform this sort of magic, or any other pointers to existing solutions?
>> >
>> >Thank you,
>> >Graham
>> >
>
