knknkn1162

$ make CROSS_COMPILE=riscv64-unknown-elf- PLATFORM=qemu/virt
 CC        lib/sbi/riscv_asm.o
 CC        lib/sbi/riscv_atomic.o
 AS        lib/sbi/riscv_hardfp.o
 CC        lib/sbi/riscv_locks.o
 CC        lib/sbi/riscv_unpriv.o
 CC        lib/sbi/sbi_console.o
 CC        lib/sbi/sbi_ecall.o
 CC        lib/sbi/sbi_emulate_csr.o
 CC        lib/sbi/sbi_fifo.o

knknkn1162

// https://www.hackerrank.com/challenges/count-triplets-1/problem
#include <assert.h>
#include <ctype.h>
#include <limits.h>
#include <math.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>

knknkn1162

```sh
make PLATFORM=qemu/virt
qemu-system-riscv64 -M virt -m 256M -nographic -kernel build/platform/qemu/virt/firmware/fw_payload.elf
```

qemu-system-riscv64: warning: No -bios option specified. Not loading a firmware.
qemu-system-riscv64: warning: This default will change in a future QEMU release. Please use the -bios option to avoid breakages when this happens.
qemu-system-riscv64: warning: See QEMU's deprecation documentation for details.

OpenSBI v0.5 (Oct 13 2019 13:07:42)

knknkn1162

$ tree ../linux-stable/arch/riscv/boot
../linux-stable/arch/riscv/boot
├── Image
├── Image.gz
├── Makefile
├── dts
│   ├── Makefile
│   └── sifive
│       ├── Makefile
│       ├── fu540-c000.dtsi

knknkn1162

qemu-system-riscv64: warning: No -bios option specified. Not loading a firmware.
qemu-system-riscv64: warning: This default will change in a future QEMU release. Please use the -bios option to avoid breakages when this happens.
qemu-system-riscv64: warning: See QEMU's deprecation documentation for details.

OpenSBI v0.5 (Oct 14 2019 06:54:36)
   ____                    _____ ____ _____
  / __ \                  / ____|  _ \_   _|
 | |  | |_ __   ___ _ __ | (___ | |_) || |
 | |  | | '_ \ / _ \ '_ \ \___ \|  _ < | |
 | |__| | |_) |  __/ | | |____) | |_) || |_

knknkn1162

alloc_page:
  - alloc_pages(gfp_mask, 0)
    - alloc_pages_node(numa_node_id()=0, gfp_mask, order=0)
      - __alloc_pages(gfp_mask, order, node_data[0]->node_zonelists + (gfp_mask & GFP_ZONEMASK));

knknkn1162

// assume that ELEVATOR_NO_MERGE
static int __make_request(request_queue_t *q, struct bio *bio)
{
	struct request *req, *freereq = NULL;
	int el_ret, rw, nr_sectors, cur_nr_sectors, barrier, err;
	sector_t sector;

	sector = bio->bi_sector;
	nr_sectors = bio_sectors(bio);
	cur_nr_sectors = bio_cur_sectors(bio);

knknkn1162

//  I/O for the block layer
struct bio {
	sector_t		bi_sector;
	struct bio		*bi_next;	/* request queue link */
	struct block_device	*bi_bdev;
	unsigned long		bi_flags;	/* status, command, etc */
	unsigned long		bi_rw;		/* bottom bits READ/WRITE,
						 * top bits priority
						 */

knknkn1162

$ ag "tty_operations"
net/irda/ircomm/ircomm_tty.c
83:static struct tty_operations ops = {

net/bluetooth/rfcomm/tty.c
877:static struct tty_operations rfcomm_ops = {

drivers/sbus/char/aurora.c
2200:static struct tty_operations aurora_ops = {

knknkn1162

struct as_rq {
	/*
	 * rbtree index, key is the starting offset
	 */
	struct rb_node rb_node;
	sector_t rb_key;

	struct request *request;

	struct io_context *io_context;	/* The submitting task */