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In the case there is just one SIMM and one memory bank from the SIMM things 

got wrong when no VRAM was there.

Placing the video DRAM in front of the kernel is OK when its 1Mb since the
kernel wants to be on a Mb boundary. Placing the video DRAM in the last
SIMM bank at the front is also OK unless there is just one SIMM and just one
bank; then it got in the way again!

Solution is to put the DRAM at the end of the SIMM instead of the beginning!
This however can result in the non 16 kb alignment of the top of physical
RAM where the temporary L1 page tables are situated. If its not 16 kb aligned
then move the L1 page table address down and down until it is 16 kb aligned.
This memory will be reused later on anyway.

What to do when we really support changing screensizes... see it as a max?
or use a different sceme alltogether? It might not even be a bootloader
problem then allthough its memory is not showing up in the DRAM/VRAM
block counts wich needs to be fixed one day.
This commit is contained in:
reinoud 2002-12-30 15:54:46 +00:00
parent 5cdedc03d0
commit 006384eaed
1 changed files with 23 additions and 16 deletions
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39
sys/arch/acorn32/stand/boot32/boot32.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: boot32.c,v 1.5 2002/12/30 03:30:16 reinoud Exp $ */
/* $NetBSD: boot32.c,v 1.6 2002/12/30 15:54:46 reinoud Exp $ */
/*-
* Copyright (c) 2002 Reinoud Zandijk
@ -340,32 +340,22 @@ void get_memory_configuration(void) {
printf(" \n\n");
/* find top of DRAM pages */
top_physdram = 0;
for (loop = podram_blocks-1; (loop >= 0) && (PODRAM_addr[loop] == 0); loop++);
if (loop >= 0) top_physdram = PODRAM_addr[loop] + PODRAM_pages[loop]*nbpp;
if (top_physdram == 0) {
for (loop = dram_blocks-1; (loop >= 0) && (DRAM_addr[loop] == 0); loop++);
if (loop >= 0) top_physdram = DRAM_addr[loop] + DRAM_pages[loop]*nbpp;
};
if (top_physdram == 0) panic("reality check: No DRAM in this machine?");
if (VRAM_pages[0] == 0) {
/* map bottom DRAM as video memory */
display_size = vdu_var(os_VDUVAR_TOTAL_SCREEN_SIZE) & ~(nbpp-1);
#if 0
mapped_screen_memory = 1024 * 1024; /* max allowed on RiscPC */
videomem_start = DRAM_addr[0];
videomem_pages = (mapped_screen_memory / nbpp);
videomem_start = DRAM_addr[0];
DRAM_addr[0] += videomem_pages * nbpp;
DRAM_pages[0] -= videomem_pages;
#else
mapped_screen_memory = display_size;
bank = dram_blocks-1; /* pick last SIMM */
videomem_start = DRAM_addr[bank];
videomem_pages = (mapped_screen_memory / nbpp);
DRAM_addr[bank] += videomem_pages * nbpp; /* at the front of the SIMM */
/* Map video memory at the end of the SIMM */
videomem_start = DRAM_addr[bank] + (DRAM_pages[bank] - videomem_pages)*nbpp;
DRAM_pages[bank]-= videomem_pages;
#endif
} else {
@ -380,6 +370,18 @@ void get_memory_configuration(void) {
printf("Used 1st Mb of DRAM at 0x%s for video memory\n", sprint0(8,'0','x', videomem_start));
};
/* find top of DRAM pages */
top_physdram = 0;
for (loop = podram_blocks-1; (loop >= 0) && (PODRAM_addr[loop] == 0); loop++);
if (loop >= 0) top_physdram = PODRAM_addr[loop] + PODRAM_pages[loop]*nbpp;
if (top_physdram == 0) {
for (loop = dram_blocks-1; (loop >= 0) && (DRAM_addr[loop] == 0); loop++);
if (loop >= 0) top_physdram = DRAM_addr[loop] + DRAM_pages[loop]*nbpp;
};
if (top_physdram == 0) panic("reality check: No DRAM in this machine?");
videomem_start_ro = vdu_var(os_VDUVAR_DISPLAY_START);
/* pretty print the individual page types */
@ -506,8 +508,13 @@ void add_pagetables_at_top(void) {
/* get 4 pages on the top of the physical memeory and copy PT's in it */
new_L1_pages_phys = top_physdram - 4*nbpp;
/* If the L1 page tables are not 16 kb aligned, adjust base until it is */
while (new_L1_pages_phys & (16*1024-1)) {
new_L1_pages_phys -= nbpp;
};
if (new_L1_pages_phys & (16*1024-1)) panic("Paranoia : L1 pages not on 16Kb boundary");
dst = new_L1_pages_phys;
if (dst & (16*1024-1)) panic("L1 pages not on 16Kb boundary");
src = (u_long) initial_page_tables;
for (page = 0; page < 4; page++) {