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Add experimental RTX 5090 (GDDR7) memory temperature support

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Reads the per-module GDDR7 DRAM sensors (FBPA DQR) directly and reports
the hotspot by default; --per-module lists each of the 8 modules.
Adds a per-device decode so the existing GDDR6/6X path is unchanged.
This commit is contained in:
Ole Algoritme
2026-07-15 15:42:23 +02:00
parent bac2c5e301
commit 9259d9a2d4
5 changed files with 151 additions and 8 deletions
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10
lib/include/gddr6.h
View File

@@ -4,11 +4,19 @@
#include <stdint.h>
// How to convert a raw register read into degrees Celsius.
enum temp_decode {
DECODE_ADA = 0, // Ada/Ampere: (raw & 0xfff) / 32
DECODE_GDDR_MRCODE, // Blackwell FBPA DQR: byte in bits 23:16 is a GDDR temp
// MR-code; C = (code-20)*2 for code>19, else -(40-code*2)
};
struct device
{
uint32_t bar0;
uint8_t bus, dev, func;
uint32_t offset;
enum temp_decode decode; // how to turn the raw reg into Celsius
uint16_t dev_id;
const char *vram;
const char *arch;
@@ -27,7 +35,7 @@ struct gddr6_ctx {
void gddr6_init(void);
void gddr6_memory_map(void);
void gddr6_cleanup(int signal);
void gddr6_monitor_temperatures(void);
void gddr6_monitor_temperatures(int per_module);
int gddr6_detect_compatible_gpus(void);
#endif // GDDR6_H

109
lib/src/gddr6.c
View File

@@ -11,7 +11,6 @@
#include <fcntl.h>
#include <sys/mman.h>
#include <pci/pci.h>
#include <signal.h>
#define PG_SZ sysconf(_SC_PAGE_SIZE)
#define PRINT_ERROR() \
@@ -23,6 +22,7 @@
#define MAX_DEVICES 32
struct gddr6_ctx ctx = {0};
// Ada/Ampere GPUs: temperature field is bits [11:0], Celsius = field / 32.
struct device dev_table[] =
{
{ .offset = 0x0000E2A8, .dev_id = 0x2684, .vram = "GDDR6X", .arch = "AD102", .name = "RTX 4090" },
@@ -49,6 +49,14 @@ struct device dev_table[] =
{ .offset = 0x0000E2A8, .dev_id = 0x27b8, .vram = "GDDR6", .arch = "AD104", .name = "L4" },
{ .offset = 0x0000E2A8, .dev_id = 0x26b9, .vram = "GDDR6", .arch = "AD102", .name = "L40S" },
{ .offset = 0x0000E2A8, .dev_id = 0x2236, .vram = "GDDR6", .arch = "GA102", .name = "A10" },
// Blackwell GDDR7 memory temperature: the raw FBPA DRAM sensor at
// NV_PFB_FBPA_DQR_STATUS_DQ_IC0_SUBP0 (0x9A24C0) - the register the FBFALCON
// firmware reads. NOT PLM-locked; reads valid data from userspace (validity
// bit 24 of 0x9A24D0). The value is a per-device GDDR temp MR-code in bits
// 23:16; DECODE_GDDR_MRCODE converts it to Celsius. (The documented mem-temp
// reg 0x9A44B0 is PLM-locked and its 0xE2A8 scratch mirror is unpopulated on
// this card, so we read the raw sensor directly.)
{ .offset = 0x009A24C0, .decode = DECODE_GDDR_MRCODE, .dev_id = 0x2b85, .vram = "GDDR7", .arch = "GB202", .name = "RTX 5090" },
};
void gddr6_init(void)
@@ -125,8 +133,77 @@ void gddr6_memory_map(void)
}
}
void gddr6_monitor_temperatures(void)
// Convert a raw register value to degrees Celsius per the device's decode.
static int decode_temp(enum temp_decode decode, uint32_t raw)
{
switch (decode)
{
case DECODE_GDDR_MRCODE:
{
// GDDR temp MR-code in bits 23:16 (see NV_PFB_FBPA_DQR_STATUS_DQ).
// code 20 = 0 C, +2 C per unit above 20; below 20 is negative.
int code = (raw >> 16) & 0xFF;
if (code > 80) code = 80;
return (code > 19) ? (code - 20) * 2 : -(40 - code * 2);
}
case DECODE_ADA:
default:
return (raw & 0x00000fff) / 0x20;
}
}
// Blackwell GDDR7 per-memory-partition (module) DQR sensors. Module p lives at
// BAR0 + DQR_MODULE0 + p*DQR_STRIDE; validity nibble (all 4 IC/subp valid = 0xF)
// is at +DQR_VLD_OFF. Unlike the single pre-mapped register, these span several
// pages, so they are read on demand with a fresh page-aligned mmap.
#define DQR_MODULE0 0x009024C0u
#define DQR_VLD_OFF (0x009024D0u - 0x009024C0u) // +0x10
#define DQR_STRIDE 0x00004000u
#define DQR_MAX_MODULES 16
// Read one 32-bit MMIO register at BAR0+off via a fresh read-only page mmap.
// Returns 0 on success. Used only for the on-demand per-module GDDR7 reads.
static int read_bar0_reg(uint32_t bar0, uint32_t off, uint32_t *out)
{
long pg = PG_SZ;
uint64_t phys = (uint64_t)bar0 + off;
uint64_t base = phys & ~((uint64_t)pg - 1);
volatile void *map = mmap(0, pg, PROT_READ, MAP_SHARED, ctx.fd, base);
if (map == MAP_FAILED) return -1;
*out = *(volatile uint32_t *)((const uint8_t *)map + (phys - base));
munmap((void *)map, pg);
return 0;
}
// Read the GDDR7 modules for a Blackwell device. Fills temps[]/present[] for up
// to DQR_MAX_MODULES, returns the module count found and the hottest temp in
// *hottest. A module counts as present only if all 4 DQR valid bits are set and
// the data word is not the 0xBADF.... poison sentinel.
static int gddr7_read_modules(uint32_t bar0, int temps[], int *hottest)
{
int count = 0, hot = -128;
for (int p = 0; p < DQR_MAX_MODULES; p++)
{
uint32_t off = DQR_MODULE0 + (uint32_t)p * DQR_STRIDE;
uint32_t vld = 0, dq = 0;
if (read_bar0_reg(bar0, off + DQR_VLD_OFF, &vld) != 0) continue;
if (read_bar0_reg(bar0, off, &dq) != 0) continue;
int all_valid = (((vld >> 24) & 0xF) == 0xF);
int poison = ((dq & 0xFFFF0000u) == 0xBADF0000u);
if (!all_valid || poison) continue;
int c = decode_temp(DECODE_GDDR_MRCODE, dq);
temps[count++] = c;
if (c > hot) hot = c;
}
*hottest = hot;
return count;
}
void gddr6_monitor_temperatures(int per_module)
{
int temps[DQR_MAX_MODULES];
while (1) {
printf("\rVRAM Temps: |");
for (uint32_t i = 0; i < ctx.num_devices; i++)
@@ -136,11 +213,31 @@ void gddr6_monitor_temperatures(void)
continue;
}
void *virt_addr = (uint8_t *) ctx.devices[i].mapped_addr + (ctx.devices[i].phys_addr - ctx.devices[i].base_offset);
uint32_t read_result = *((uint32_t *)virt_addr);
uint32_t temp = ((read_result & 0x00000fff) / 0x20);
// Blackwell GDDR7: per-module DQR sensors. Default shows the hotspot
// (max across modules); --per-module lists each module.
if (ctx.devices[i].decode == DECODE_GDDR_MRCODE)
{
int hottest = 0;
int n = gddr7_read_modules(ctx.devices[i].bar0, temps, &hottest);
if (n == 0) { printf(" n/a |"); continue; }
printf(" %3u°C |", temp);
if (per_module)
{
for (int m = 0; m < n; m++)
printf(" m%d=%3d°C |", m, temps[m]);
}
else
{
printf(" %3d°C (hotspot) |", hottest);
}
continue;
}
// Ada/Ampere: single pre-mapped VRAM register.
void *virt_addr = (uint8_t *) ctx.devices[i].mapped_addr + (ctx.devices[i].phys_addr - ctx.devices[i].base_offset);
uint32_t read_result = *((uint32_t *)virt_addr);
int temp = decode_temp(ctx.devices[i].decode, read_result);
printf(" %3d°C |", temp);
}
fflush(stdout);
sleep(1);