[Qemu-devel] Re: Accessing the serial port from proll

[Qemu-devel] Re: Accessing the serial port from proll

[Blue Swirl]

Hi,

I guess you are not using Qemu's -nographic option. The flag is passed on to 
Proll, which then initialises either serial port or frame buffer 
accordingly.

For example, the following code echoes serial port data back:

diff -ru proll-patch-16/qemu/main.c proll-patch-16b/qemu/main.c
--- proll-patch-16/qemu/main.c  2005-08-14 10:07:48.000000000 +0000
+++ proll-patch-16b/qemu/main.c 2005-11-20 08:50:57.000000000 +0000
@@ -79,6 +79,13 @@
        ram_size = ld_bypass(PHYS_JJ_EEPROM + 0x30);
        printk("%d MB total\n", ram_size/(1024*1024));

+       for (;;) {
+               int ch;
+
+               ch = vcon_zs_getch(&dp0);
+               vcon_zs_putch(&dp0, ch);
+       }
+
        bb.nbanks = 1;
        bb.bankv[0].start = 0;
        bb.bankv[0].length = ram_size;

I think serial loader would be nice addition, though there is already CD/HD 
(no FD) and network boot options. If you don't care about Sun OBP 
compatibility, I'd suggest reusing GDB remote debugging code.

Or are you trying to use Proll on Sparc64? In that case the serial port is 
not Zilog one, but PC-compatible (vcons_su).

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[Qemu-devel] Re: Accessing the serial port from proll

[Doug Gray]

Hi,

Thanks for the help.  I've actually tried using the function you 
suggest, but gotten the following error:

sparc-elf-gcc -O1 -W -Wall -DPROLBASE=0xffd00000 -DPROLDATA=0xffd0b000 
-DPROLRODATA=0xffd08000 -D__ANSI__=1 -I../src -mcpu=hypersparc 
-Wa,-xarch=v8 -g -DQEMU -m32 -fno-builtin -c main.c
sparc-elf-ld -N -Ttext 0xffd00000 --section-start .rodata=0xffd08000 
-Tdata 0xffd0b000 -Tbss 0xffd0b000 -o proll.elf head.o wuf.o wof.o 
main.o  printf.o le.o system_qemu.o iommu.o arp.o netinit.o bootp.o 
packet.o tftp.o udp.o sched_4m.o openprom.o vconsole.o hconsole.o 
rconsole.o vcons_zs.o esp.o
sparc-elf-ld: section .rodata [00000000ffd08000 -> 00000000ffd0a129] 
overlaps section .text [00000000ffd00000 -> 00000000ffd08077]
sparc-elf-ld: proll.elf: section .rodata lma 0xffd08000 overlaps 
previous sections
make: *** [proll.elf] Error 1

However when I tried your code snippet it works fine.  It seems that it 
only works if I call that function from an infinite loop (big loop or 
loops with a break statement don't compile either), which is driving me 
nuts.  Do you know why this is?

Also, some additional background info.  I am actually using the 
-nographic option.  This project is for a grad class on computer 
architecture.  The prof. says he has a sparc processor implemented on an 
fpga and wants to load linux on it, but it doesn't have a hard drive or 
network connection, so that is why I'm writing a serial loader.

-Doug

[Qemu-devel] Re: Accessing the serial port from proll

[Blue Swirl]

>sparc-elf-ld: section .rodata [00000000ffd08000 -> 00000000ffd0a129] 
>overlaps section .text [00000000ffd00000 -> 00000000ffd08077]

This means that the space reserved for code is full. You can adjust it like 
this:

diff -ru proll-patch-16/qemu/Makefile proll-patch-16b/qemu/Makefile
--- proll-patch-16/qemu/Makefile        2005-08-14 10:25:06.000000000 +0000
+++ proll-patch-16b/qemu/Makefile       2005-11-20 12:23:46.000000000 +0000
@@ -27,8 +27,8 @@
# want to shift it to form a PGD entry. A relocatable label will not work.
# Linux kernel expects us to be at LINUX_OPPROM_BEGVM 
<asm-sparc/openprom.h>.
PROLBASE =   0xffd00000
-PROLRODATA = 0xffd08000
-PROLDATA =   0xffd0b000
+PROLRODATA = 0xffd09000
+PROLDATA =   0xffd0c000
PROLSIZE = 240*1024

# Linux

>Also, some additional background info.  I am actually using the -nographic 
>option.  This project is for a grad class on computer architecture.  The 
>prof. says he has a sparc processor implemented on an fpga and wants to 
>load linux on it, but it doesn't have a hard drive or network connection, 
>so that is why I'm writing a serial loader.

Real serial port hardware needs a bit more initialising than Qemu, for 
example programming the baud rate. In the original JavaStation case where 
Proll was first used, the real OBP did this before Proll booted, so Proll 
didn't have to do everything.

There are probably other similar gaps elsewhere, like setting up DRAM 
controllers, clearing special boot modes, initialising bridge devices, 
loading firmware etc. If you have complete specs for the hardware, these 
should not be too difficult to add if even necessary.

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