* [PATCH] added the inpsect block command ('xb') to print the contents within a block device to the monitor.
@ 2026-07-27 2:47 Tripp R
0 siblings, 0 replies; only message in thread
From: Tripp R @ 2026-07-27 2:47 UTC (permalink / raw)
To: qemu-devel; +Cc: Dr. David Alan Gilbert, Tripp R
'xb' (examine block) is almost identical in usage to 'x' and 'xp', having the same targuments for those commands , albeit preceded by a drive name.
---
Implemented the xb (examine block) command to print the contents of a block device to the console.
It is effectively a clone of the x/xp commands (examine memory / examine physical memory), having the same arguments for those commands, albeit preceded by the name of a block driver.
e.g. usage
xd floppy0 /510c 0
Signed-off-by: Tripp R <tripprobins@gmail.com>
---
hmp-commands.hx | 14 +++++++
include/monitor/hmp.h | 1 +
monitor/hmp-cmds.c | 104 ++++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 119 insertions(+)
diff --git a/hmp-commands.hx b/hmp-commands.hx
index 7ae2468a3d..db63b58a47 100644
--- a/hmp-commands.hx
+++ b/hmp-commands.hx
@@ -472,6 +472,20 @@ ERST
.cmd = hmp_memory_dump,
},
+SRST
+``xb/``\ *fmt* *addr*
+ Block memory dump starting at *addr*.
+ERST
+
+ {
+ .name = "xb",
+ .args_type = "device:s, fmt:/,addr:l",
+ .params = "device /fmt addr",
+ .help = "block memory dump starting at 'addr'",
+ .cmd = hmp_block_dump,
+ },
+
+
SRST
``x/``\ *fmt* *addr*
Virtual memory dump starting at *addr*.
diff --git a/include/monitor/hmp.h b/include/monitor/hmp.h
index 9258a049bf..0c3e8a30c2 100644
--- a/include/monitor/hmp.h
+++ b/include/monitor/hmp.h
@@ -182,6 +182,7 @@ void hmp_info_local_apic(Monitor *mon, const QDict *qdict);
void hmp_info_sev(Monitor *mon, const QDict *qdict);
void hmp_info_sgx(Monitor *mon, const QDict *qdict);
void hmp_info_via(Monitor *mon, const QDict *qdict);
+void hmp_block_dump(Monitor *mon, const QDict *qdict);
void hmp_memory_dump(Monitor *mon, const QDict *qdict);
void hmp_physical_memory_dump(Monitor *mon, const QDict *qdict);
void hmp_info_registers(Monitor *mon, const QDict *qdict);
diff --git a/monitor/hmp-cmds.c b/monitor/hmp-cmds.c
index e9fb8d827a..5d4a6c6a78 100644
--- a/monitor/hmp-cmds.c
+++ b/monitor/hmp-cmds.c
@@ -39,8 +39,12 @@
#include "system/hw_accel.h"
#include "system/memory.h"
#include "system/system.h"
+#include "system/block-backend-common.h"
+#include "system/block-backend-io.h"
+#include "system/block-backend-global-state.h"
#include "disas/disas.h"
+
/* Please update hmp-commands.hx when adding or changing commands */
static HMPCommand hmp_info_cmds[] = {
#include "hmp-commands-info.h"
@@ -584,6 +588,89 @@ void hmp_info_registers(Monitor *mon, const QDict *qdict)
}
}
+
+static void block_dump(Monitor *mon, BlockBackend* blk, int count, int format,
+ int wsize, int64_t offset)
+{
+ uint8_t buf[16];
+
+ uint16_t max_digits = 0;
+
+ switch (format) {
+ case 'o':
+ max_digits = DIV_ROUND_UP(wsize * 8, 3);
+ break;
+ default:
+ case 'x':
+ max_digits = (wsize * 8) / 4;
+ break;
+ case 'u':
+ case 'd':
+ max_digits = DIV_ROUND_UP(wsize * 8 * 10, 33);
+ break;
+ case 'c':
+ wsize = 1;
+ break;
+ }
+
+
+ while (count > 0) {
+ int bytes = MIN(16, count * wsize);
+
+ if (blk_pread(blk, offset, bytes, buf, 0) < 0) {
+ monitor_printf(mon,
+ "Read failed at 0x%" PRIx64 "\n",
+ offset);
+ return;
+ }
+
+ monitor_printf(mon, "%08" PRIx64 ": ", offset);
+
+ for (int i = 0; i < bytes; i += wsize) {
+ uint64_t v;
+
+ switch (wsize) {
+ case 1:
+ v = buf[i];
+ break;
+ case 2:
+ v = lduw_le_p(buf + i);
+ break;
+ case 4:
+ v = ldl_le_p(buf + i);
+ break;
+ case 8:
+ v = ldq_le_p(buf + i);
+ break;
+ default:
+ v=0;
+ }
+ switch (format) {
+ case 'o':
+ monitor_printf(mon, "0%*" PRIo64, max_digits, v);
+ break;
+ case 'x':
+ monitor_printf(mon, "0x%0*" PRIx64, max_digits, v);
+ break;
+ case 'u':
+ monitor_printf(mon, "%*" PRIu64, max_digits, v);
+ break;
+ case 'd':
+ monitor_printf(mon, "%*" PRId64, max_digits, v);
+ break;
+ case 'c':
+ monitor_printc(mon, v);
+ break;
+ }
+ }
+
+ monitor_printf(mon, "\n");
+
+ offset += bytes;
+ count -= bytes / wsize;
+ }
+}
+
static void memory_dump(Monitor *mon, int count, int format, int wsize,
uint64_t addr, bool is_physical)
{
@@ -692,6 +779,23 @@ static void memory_dump(Monitor *mon, int count, int format, int wsize,
}
}
+void hmp_block_dump(Monitor *mon, const QDict *qdict)
+{
+ int count = qdict_get_int(qdict, "count");
+ int format = qdict_get_int(qdict, "format");
+ int size = qdict_get_int(qdict, "size");
+ vaddr addr = qdict_get_int(qdict, "addr");
+ const char* dblock = qdict_get_str(qdict, "device");
+
+ BlockBackend *blk = blk_by_name(dblock);
+
+ if (!blk) {
+ monitor_printf(mon, "Invalid block device name '%s'.\n\r", dblock);
+ return;
+ }
+ block_dump(mon,blk, count, format, size, addr);
+}
+
void hmp_memory_dump(Monitor *mon, const QDict *qdict)
{
int count = qdict_get_int(qdict, "count");
---
base-commit: 443e02410695b35a27fad18217424b6370358be7
change-id: 20260726-xbcmd-7fa889067f15
Best regards,
--
Tripp R <tripprobins@gmail.com>
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2026-07-27 2:47 [PATCH] added the inpsect block command ('xb') to print the contents within a block device to the monitor Tripp R
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