Evan Felix wrote:
> Folks here is a patch i've made for qemu that adds a memory based
> block device, it utilizes memory on the Host side to emulate a block
> device.
>
I often use -hda /dev/null for -kernel/-append.
If you really want to implement a "proper" solution for -kernel/-append,
I think the right thing to do would be to use an option ROM instead of a
fake boot sector.
Regards,
Anthony Liguori
> I've tested this on a few boxes to allow a kernel/initramfs system to
> boot without needing a specified block device(it automatically creates
> a small one) and for installing a usable system on. One note you can
> never shut down the running system, but seems to work fine when only
> re-boots are required. I've installed debian on it a few times.
>
> Some Things I'd like comments on:
> - The auto-detection code in the block code causes the code to
> allocate the memory used twice, even though it only gets used the
> second time.
> - using qemu_mallocz seems to pre-allocate all the memory used, which
> is fine, but my early code with calloc only allocated what blocks were
> actually used. Does this bother people.
>
> Evan Felix
>
>
> diff -urNp -x '*~' -x '*html' -x '*.mak' -x '*.1'
> kvm-28/qemu.orig/block.c kvm-28/qemu/block.c
> --- kvm-28/qemu.orig/block.c 2007-06-07 08:13:47.000000000 -0700
> +++ kvm-28/qemu/block.c 2007-07-11 13:29:02.000000000 -0700
> @@ -1244,6 +1244,7 @@ static int bdrv_write_em(BlockDriverStat
> void bdrv_init(void)
> {
> bdrv_register(&bdrv_raw);
> + bdrv_register(&bdrv_mem);
> bdrv_register(&bdrv_host_device);
> #ifndef _WIN32
> bdrv_register(&bdrv_cow);
> diff -urNp -x '*~' -x '*html' -x '*.mak' -x '*.1'
> kvm-28/qemu.orig/block-mem.c kvm-28/qemu/block-mem.c
> --- kvm-28/qemu.orig/block-mem.c 1969-12-31 16:00:00.000000000 -0800
> +++ kvm-28/qemu/block-mem.c 2007-07-09 13:46:39.000000000 -0700
> @@ -0,0 +1,129 @@
> +/*
> + * Block Driver for a Memory disk on the host side.
> + *
> + * Copyright (c) 2007 Pacific Northwest National Laboratory
> + * and Evan Felix <[EMAIL PROTECTED]>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program (see the file COPYING included with this
> + * distribution); if not, write to the Free Software Foundation, Inc.,
> + * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
> + */
> +
> +#include "vl.h"
> +#include "block_int.h"
> +
> +//I took this from block-raw.c
> +#ifdef __sun__
> +#define _POSIX_PTHREAD_SEMANTICS 1
> +#include <signal.h>
> +#include <sys/dkio.h>
> +#endif
> +#ifdef __linux__
> +#include <sys/ioctl.h>
> +#include <linux/cdrom.h>
> +#include <linux/fd.h>
> +#endif
> +#ifdef __FreeBSD__
> +#include <sys/disk.h>
> +#endif
> +
> +#define DEBUG_MEM 0
> +
> +#ifdef DEBUG_MEM
> +#define DEBUG(fmt,a...) printf("D:%s:%d> " fmt "\n",__FILE__,__LINE__,##a)
> +#else
> +#define DEBUG(fmt,a...)
> +#endif
> +
> +typedef struct BDRVMemState {
> + void *memory;
> + int64_t length;
> +} BDRVMemState;
> +
> +static int mem_open(BlockDriverState *bs, const char *filename, int flags)
> +{
> + BDRVMemState *s = bs->opaque;
> +
> + bs->locked = 1;
> + bs->type = BDRV_TYPE_HD;
> + //Try to parse the filename as a number of bytes. add recognize M,K,G
> laterz.
> + s->length = strtol(filename+4,NULL,0);
> + DEBUG("mem_open:Raw Image size: %s -> %ld\n",filename,s->length);
> +
> + s->memory=qemu_mallocz(s->length);
> + if (! s->memory)
> + return -ENOMEM;
> + return 0;
> +}
> +
> +static void mem_close(BlockDriverState *bs) {
> +
> + BDRVMemState *s = bs->opaque;
> + DEBUG("mem_close: %lld\n",s->length);
> + qemu_free(s->memory);
> + s->length=0;
> +}
> +
> +static int mem_pread(BlockDriverState *bs, int64_t offset,
> + uint8_t *buf, int count)
> +{
> + BDRVMemState *s = bs->opaque;
> +
> + if (offset < 0 || (offset + count)>s->length) {
> + return -EINVAL;
> + }
> +
> + memcpy(buf,(s->memory+offset),count);
> + return count;
> +}
> +
> +static int mem_pwrite(BlockDriverState *bs, int64_t offset,
> + const uint8_t *buf, int count)
> +{
> + BDRVMemState *s = bs->opaque;
> +
> + if (offset < 0 || (offset + count)>s->length) {
> + return -EINVAL;
> + }
> +
> + memcpy((s->memory+offset),buf,count);
> + return count;
> +}
> +
> +static void mem_flush(BlockDriverState *bs)
> +{
> + //Do Nothing for now
> + DEBUG("mem_flush\n");
> +}
> +
> +static int64_t mem_getlength(BlockDriverState *bs)
> +{
> + BDRVMemState *s = bs->opaque;
> +
> + return s->length;
> +}
> +
> +BlockDriver bdrv_mem = {
> + .format_name = "mem",
> + .instance_size = sizeof(BDRVMemState),
> + .protocol_name = "mem",
> +
> + .bdrv_open = mem_open,
> + .bdrv_close = mem_close,
> + .bdrv_flush = mem_flush,
> +
> + .bdrv_pread = mem_pread,
> + .bdrv_pwrite = mem_pwrite,
> + .bdrv_getlength = mem_getlength,
> +};
> diff -urNp -x '*~' -x '*html' -x '*.mak' -x '*.1'
> kvm-28/qemu.orig/hw/pc.c kvm-28/qemu/hw/pc.c
> --- kvm-28/qemu.orig/hw/pc.c 2007-06-07 08:13:47.000000000 -0700
> +++ kvm-28/qemu/hw/pc.c 2007-07-06 16:48:12.000000000 -0700
> @@ -583,8 +583,13 @@ static void pc_init1(int ram_size, int v
> uint8_t old_bootsect[512];
>
> if (bs_table[0] == NULL) {
> - fprintf(stderr, "A disk image must be given for 'hda'
> when booting a Linux kernel\n");
> - exit(1);
> + fprintf(stderr, "A disk image must be given when booting
> a Linux kernel....\n\tCreating Simple memory backed Disk\n");
> + bs_table[i] = bdrv_new("hda");
> + if (bdrv_open(bs_table[0], "mem:4096", 0) < 0) {
> + fprintf(stderr, "qemu: could not open hard disk image
> '%s'\n",
> + "mem:512");
> + exit(1);
> + }
> }
> snprintf(buf, sizeof(buf), "%s/%s", bios_dir, LINUX_BOOT_FILENAME);
> ret = load_image(buf, bootsect);
> diff -urNp -x '*~' -x '*html' -x '*.mak' -x '*.1'
> kvm-28/qemu.orig/Makefile kvm-28/qemu/Makefile
> --- kvm-28/qemu.orig/Makefile 2007-06-07 08:13:47.000000000 -0700
> +++ kvm-28/qemu/Makefile 2007-07-06 14:24:44.000000000 -0700
> @@ -39,7 +39,7 @@ subdir-%: dyngen$(EXESUF)
>
> recurse-all: $(patsubst %,subdir-%, $(TARGET_DIRS))
>
> -qemu-img$(EXESUF): qemu-img.c cutils.c block.c block-raw.c
> block-cow.c block-qcow.c aes.c block-vmdk.c block-cloop.c block-dmg.c
> block-bochs.c block-vpc.c block-vvfat.c block-qcow2.c
> +qemu-img$(EXESUF): qemu-img.c cutils.c block.c block-raw.c
> block-cow.c block-qcow.c aes.c block-vmdk.c block-cloop.c block-dmg.c
> block-bochs.c block-vpc.c block-vvfat.c block-qcow2.c block-mem.c
> $(CC) -DQEMU_TOOL $(CFLAGS) $(CPPFLAGS) $(BASE_CFLAGS) $(LDFLAGS)
> $(BASE_LDFLAGS) -o $@ $^ -lz $(LIBS)
>
> dyngen$(EXESUF): dyngen.c
> diff -urNp -x '*~' -x '*html' -x '*.mak' -x '*.1'
> kvm-28/qemu.orig/Makefile.target kvm-28/qemu/Makefile.target
> --- kvm-28/qemu.orig/Makefile.target 2007-06-07 08:13:47.000000000 -0700
> +++ kvm-28/qemu/Makefile.target 2007-07-06 13:43:31.000000000 -0700
> @@ -326,7 +326,7 @@ endif
> VL_OBJS=vl.o osdep.o readline.o monitor.o pci.o console.o loader.o isa_mmio.o
> VL_OBJS+=cutils.o migration.o
> VL_OBJS+=block.o block-raw.o
> -VL_OBJS+=block-cow.o block-qcow.o aes.o block-vmdk.o block-cloop.o
> block-dmg.o block-bochs.o block-vpc.o block-vvfat.o block-qcow2.o
> +VL_OBJS+=block-cow.o block-qcow.o aes.o block-vmdk.o block-cloop.o
> block-dmg.o block-bochs.o block-vpc.o block-vvfat.o block-qcow2.o
> block-mem.o
> ifdef CONFIG_WIN32
> VL_OBJS+=tap-win32.o
> endif
> diff -urNp -x '*~' -x '*html' -x '*.mak' -x '*.1'
> kvm-28/qemu.orig/vl.h kvm-28/qemu/vl.h
> --- kvm-28/qemu.orig/vl.h 2007-06-07 08:13:47.000000000 -0700
> +++ kvm-28/qemu/vl.h 2007-07-06 14:23:50.000000000 -0700
> @@ -561,6 +561,7 @@ typedef struct BlockDriverState BlockDri
> typedef struct BlockDriver BlockDriver;
>
> extern BlockDriver bdrv_raw;
> +extern BlockDriver bdrv_mem;
> extern BlockDriver bdrv_host_device;
> extern BlockDriver bdrv_cow;
> extern BlockDriver bdrv_qcow;
>
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