Thanks a lot for your reply.
On Thu, Feb 10, 2011 at 3:31 PM, Kevin O'Connor kevin@koconnor.net wrote:
On Mon, Feb 07, 2011 at 07:17:52PM +0000, Prasad Joshi wrote:
Hello,
As I notice on my host machine the same case happens, but host BIOS seems to be allocating 128MB memory from some other region (c0000000-c7ffffff)
[...]
Can SeaBIOS do the same thing? or to put in other words Can SeaBIOS allocate memory from some other region instead of fixed f0000000 to (0xfec00000-1)?
It should be possible to alter BUILD_PCIMEM_START in src/config.h. The reason it is at 0xf0000000 is because regular memory can go up to 0xe0000000, and the bochs vga bios had soe dependency on the address space at 0xe0000000 - though this may no longer be the case.
I modified the memory range according the lspci -vv output. Atleast on my machine, the memory range 0xf0000000 to 0xfec00000 is reserved for non-prefectable memory.
Here is a small modification. As long as it keeps the behavior for old pci assignments, I guess this would not be a problem.
diff --git a/src/config.h b/src/config.h index 5b40488..19729cb 100644 --- a/src/config.h +++ b/src/config.h @@ -49,20 +49,18 @@
// Support old pci mem assignment behaviour //#define CONFIG_OLD_PCIMEM_ASSIGNMENT 1 -#if CONFIG_OLD_PCIMEM_ASSIGNMENT #define BUILD_PCIMEM_START 0xf0000000 #define BUILD_PCIMEM_SIZE (BUILD_PCIMEM_END - BUILD_PCIMEM_START) #define BUILD_PCIMEM_END 0xfec00000 /* IOAPIC is mapped at */ + +#if CONFIG_OLD_PCIMEM_ASSIGNMENT #define BUILD_PCIPREFMEM_START 0 #define BUILD_PCIPREFMEM_SIZE 0 #define BUILD_PCIPREFMEM_END 0 #else -#define BUILD_PCIMEM_START 0xf0000000 -#define BUILD_PCIMEM_SIZE 0x08000000 /* half- of pci window */ -#define BUILD_PCIMEM_END (BUILD_PCIMEM_START + BUILD_PCIMEM_SIZE) -#define BUILD_PCIPREFMEM_START BUILD_PCIMEM_END +#define BUILD_PCIPREFMEM_START 0xc0000000 #define BUILD_PCIPREFMEM_SIZE (BUILD_PCIPREFMEM_END - BUILD_PCIPREFMEM_START) -#define BUILD_PCIPREFMEM_END 0xfec00000 /* IOAPIC is mapped at */ +#define BUILD_PCIPREFMEM_END 0xdfffffff #endif
#define BUILD_APIC_ADDR 0xfee00000
Also, in the function pci_bios_allocate_region(), discards the prefectable memory region and places it in the non-prefectable memory region, if the bus is 0.
} else if ((val & PCI_BASE_ADDRESS_MEM_PREFETCH) && /* keep behaviour on bus = 0 */ pci_bdf_to_bus(bdf) != 0 && /* If pci_bios_prefmem_addr == 0, keep old behaviour */ pci_region_addr(&pci_bios_prefmem_region) != 0) {
I am not sure if this can be changed, can you please shade more light on this?
-Kevin