On Thu, Nov 24, 2005 at 08:29:53PM +0100, Andi Kleen wrote:
> > We implemented AMD's reference algorithm, and made it work in the presence
> > of a hardware IO hole. It seems to work beautifully, but the last step is
> > turning a (node:chip-select) into a (node:dimm). Simple boards will use
> > simple mappings, but we can't know that without board specific info.
> > Especially with quad-rank DIMMs. :)
>
> If you get something working it would be good if you could share the code
> (even if it still needs to be tweaked)
The below code works for us. Note that I did not implement the
node-interleaving parts of the AMD algorithm. If that matters, it should
be simple enough to do. The BKDG has good pseudo-code. The only thing it
gets absolutely wrong is the IO hole.
Let me know if you see any problems here. This is a userspace tool, but
should be trivial to adapt.
#include <stdio.h>
#include <stdlib.h>
#include "pci.h"
#define MAX_NODES 8
#define MAX_CS 8
#define NODE_DEV(n) (24+(n))
#define FOUR_GIG 0x01000000 // shifted to hold address[39..8]
static char *progname;
static void
usage(void)
{
fprintf(stderr, "usage: %s <address>\n", progname);
}
/*
* Map a CS to a pair of DIMM slots (for 128 bit operation). This mapping
* is board-specific, and has the potential to be very ugly.
*/
static int cs_to_pair[MAX_CS][2] = {
{ 0, 1 }, { 0, 1 },
{ 2, 3 }, { 2, 3 },
{ 4, 5 }, { 4, 5 },
{ 6, 7 }, { 6, 7 },
};
int
main(int argc, char *argv[])
{
unsigned long long raw_addr;
uint32_t address;
char *endp;
int node;
progname = argv[0];
if (argc != 2) {
usage();
exit(1);
}
raw_addr = strtoull(argv[1], &endp, 0);
if (endp == argv[1]) {
usage();
exit(2);
}
/*
* The address space is 40 bits (for now). We want to use 32 bit
* values, so we convert the input address to hold address[39..8].
* We'll use this format everywhere. This loses the
* low-order bits, so we keep a raw copy around.
*/
address = (raw_addr & 0xffffffffff) >> 8;
/* find the node that holds this address */
for (node = 0; node < MAX_NODES; node++) {
int pci_dev;
uint32_t tmp;
int dram_en;
uint32_t dram_base;
uint32_t dram_limit;
int hole_en;
uint32_t hole_base;
uint32_t hole_size;
int cs;
/*
* The DRAM map and IO hole info are in function 1 of each
* node.
*/
pci_dev = pci_open(0, NODE_DEV(node), 1);
if (pci_dev < 0) {
/* node does not exist */
break;
}
/*
* DRAM_BASE and DRAM_LIMIT already hold address[39..8].
*/
tmp = pci_read32(pci_dev, 0x40+(node*8));
dram_en = tmp & 0x3;
dram_base = tmp & 0xffff0000;
tmp = pci_read32(pci_dev, 0x44+(node*8));
dram_limit = tmp | 0x0000ffff;
/*
* HOLE_BASE holds address[35..4], so we convert it to hold
* address[39..8].
*/
tmp = pci_read32(pci_dev, 0xf0);
hole_en = tmp & 0x1;
hole_base = (tmp & 0xff000000) >> 8;
hole_size = FOUR_GIG - hole_base;
pci_close(pci_dev);
if (!dram_en) {
/* no DRAM here */
continue;
}
if (address > dram_limit) {
/* keep looking */
continue;
}
/*
* The address must be on this node.
*/
/* is the address in the IO hole? */
if (hole_en && address >= hole_base && address < FOUR_GIG) {
/* no DRAM in the IO hole */
break;
}
/* is the address >= 4GB on a node with a hole? */
if (hole_en && address >= FOUR_GIG) {
/* adjust address for the IO hole */
address -= hole_size;
}
/* adjust address to be node-relative */
address -= dram_base;
/* store addr[35..4] */
address <<= 4;
/* The chip-select map is in function 2 of each node. */
pci_dev = pci_open(0, NODE_DEV(node), 2);
/* find the chip-select that has this address */
for (cs = 0; cs < MAX_CS; cs++) {
uint32_t cs_base;
uint32_t cs_mask;
/*
* CS_BASE and CS_MASK hold address[35..0], so we
* convert them to hold address[39..8].
*/
tmp = pci_read32(pci_dev, 0x40+(cs*4));
if ((tmp & 0x1) == 0) {
/* this CS is not enabled */
continue;
}
cs_base = tmp & 0xffe0fe00;
tmp = pci_read32(pci_dev, 0x60+(cs*4));
cs_mask = (tmp | 0x001f01ff) & 0x3fffffff;
/* this should handle interleaving, too */
if ((address & ~cs_mask) == (cs_base & ~cs_mask)) {
int *pair = cs_to_pair[cs];
int dimm;
/* which DIMM is this address on? */
if ((raw_addr & (1<<3)) == 0) {
dimm = pair[0];
} else {
dimm = pair[1];
}
printf("node %d, CS %d, DIMM %d\n",
node, cs, dimm);
break;
}
}
pci_close(pci_dev);
break;
}
return 0;
}
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