[LinuxBIOS] The two load RAM codes.

[Lu, Yinghai]

LinuxBIOS have three parts

1.	linuxbios for init RAM, and Cache_as_RAM. Code is Flash, and
stack is in CACHE. From cache_as_ram_main()
2.	linuxbios_ram: for PCI device handling. ---  from hardwaremain()
Code is in ram and unzipped from rom by 1.
3.	payload: it could be Etherboot ( boot from Network) or Kernel.
Elfloader in 2 will load payload and jmp to it.

 

Also the flash will contain three linuxbios.rom

Normal+Fallback+Failover.

Failover will be used to init 64K above rom access.

 

YH

 

________________________________

From: linuxbios-bounces at linuxbios.org
[mailto:linuxbios-bounces at linuxbios.org] On Behalf Of Feng, Libo
Sent: Thursday, February 01, 2007 8:16 PM
To: linuxbios at linuxbios.org
Subject: [LinuxBIOS] The two load RAM codes.

 

 

I am studying the LinuxBios project. I have a question about the RAM
code: from Makefile, it seems that LinuxBios could load codes from FLASH
to RAM twice, first for linuxbios_ram, second for so-called payload. My
understanding is correct or not. However, also from Makefile, it seems
that linuxbios is dependent on LINUXBIOS_RAM_ROM, but doesn't include
it. The below is abstracted from a Makefile for via epia-m based on
LinuxBiosV2-2534:

linuxbios: crt0.o $(INIT-OBJECTS) $(LINUXBIOS_APC) $(LINUXBIOS_RAM_ROM)
ldscript.ld
        $(CC) -nostdlib -nostartfiles -static -o $@ -T ldscript.ld
crt0.o $(INIT-OBJECTS)
        $(CROSS_COMPILE)nm -n linuxbios | sort > linuxbios.map. 

So, there is no action on LINUXBIOS_RAM_ROM. Does it mean linuxbios_ram
is not very important. Even without it, the system is also ok?

Feng Libo 

 

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