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 <address@hidden>
+ *
+ * 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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