knurling-rs · jonathanpallant · Nov 7, 2025 · Nov 7, 2025 · Nov 7, 2025 · Nov 7, 2025
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -24,6 +24,7 @@ We have several packages which live in this repository. Changes are tracked sepa
 * [defmt-test](#defmt-test)
 * [defmt-test-macros](#defmt-test-macros)
 * [defmt-json-schema](#defmt-json-schema)
+* [qemu-run](#qemu-run)
 * [defmt-elf2table](#defmt-elf2table)
 * [defmt-logger](#defmt-logger)
 
@@ -944,6 +945,21 @@ Initial release
 
 Initial release
 
+## qemu-run
+
+> Runs [`qemu-system-arm`] but decodes [`defmt`] data sent to semihosting
+
+[qemu-run-next]: https://github.com/knurling-rs/defmt/compare/qemu-run-v0.1.0...main
+[qemu-run-v0.1.0]: https://github.com/knurling-rs/defmt/releases/tag/qemu-run-v0.1.0
+
+### [qemu-run-next]
+
+* No changes
+
+### [qemu-run-v0.1.0]
+
+Initial release
+
 ## defmt-elf2table
 
 > Reads ELF metadata and builds a defmt interner table

diff --git a/Cargo.lock b/Cargo.lock
diff --git a/decoder/src/log/format/mod.rs b/decoder/src/log/format/mod.rs
@@ -430,7 +430,7 @@ impl InternalFormatter {
                     DefaultStyle::get_string(with_location, config.is_timestamp_available)
                         .to_string();
                 if source == Source::Host {
-                    format.insert_str(0, "(HOST) ");
+                    format.push_str(" (HOST)");
                 }
 
                 format
@@ -441,7 +441,7 @@ impl InternalFormatter {
                         .to_string();
 
                 if source == Source::Host {
-                    format.insert_str(0, "(HOST) ");
+                    format.push_str(" (HOST)");
                 }
 
                 format

diff --git a/firmware/qemu/.cargo/config.toml b/firmware/qemu/.cargo/config.toml
@@ -5,7 +5,7 @@ rrb = "-q run --target thumbv7m-none-eabi --release --bin"
 
 [target.'cfg(all(target_arch = "arm", target_os = "none"))']
 # runner = "qemu-system-arm -cpu cortex-m3 -machine lm3s6965evb -nographic -semihosting-config enable=on,target=native -kernel"
-runner = "cargo -q run --manifest-path ../../qemu-run/Cargo.toml"
+runner = "cargo -q run --manifest-path ../../qemu-run/Cargo.toml -- --machine lm3s6965evb --verbose"
 
 rustflags = [
   # LLD (shipped with the Rust toolchain) is used as the default linker

diff --git a/firmware/qemu/src/bin/alloc.out b/firmware/qemu/src/bin/alloc.out
@@ -1,15 +1,15 @@
-0.000000 INFO Box<u32>: 42
-0.000001 INFO Box<Box<u32>>: 1337
-0.000002 INFO in nested 123
-0.000003 INFO Box<NestedStruct>: NestedStruct { a: 170, b: 305419896 }
-0.000004 INFO Rc<u32>: 42
-0.000005 INFO Arc<u32>: 42
-0.000006 INFO Vec<u32>: [1, 2, 3, 4]
-0.000007 INFO Vec<i32>: [-1, 2, 3, 4]
-0.000008 INFO Vec<Box<i32>>: [-1, 2, 3, 4]
-0.000009 INFO Box<Vec<i32>>: [-1, 2, 3, 4]
-0.000010 INFO String: Hello! I'm a heap-allocated String
-0.000011 INFO Cow<[u32]>: [1, 2, 3, 4]
-0.000012 INFO Cow<Vec<u32>>: [1, 2, 3, 4]
-0.000013 INFO Cow<str>: moo
-0.000014 INFO Cow<String>: moo, but allocated
+0.000000 INFO  Box<u32>: 42
+0.000001 INFO  Box<Box<u32>>: 1337
+0.000002 INFO  in nested 123
+0.000003 INFO  Box<NestedStruct>: NestedStruct { a: 170, b: 305419896 }
+0.000004 INFO  Rc<u32>: 42
+0.000005 INFO  Arc<u32>: 42
+0.000006 INFO  Vec<u32>: [1, 2, 3, 4]
+0.000007 INFO  Vec<i32>: [-1, 2, 3, 4]
+0.000008 INFO  Vec<Box<i32>>: [-1, 2, 3, 4]
+0.000009 INFO  Box<Vec<i32>>: [-1, 2, 3, 4]
+0.000010 INFO  String: Hello! I'm a heap-allocated String
+0.000011 INFO  Cow<[u32]>: [1, 2, 3, 4]
+0.000012 INFO  Cow<Vec<u32>>: [1, 2, 3, 4]
+0.000013 INFO  Cow<str>: moo
+0.000014 INFO  Cow<String>: moo, but allocated
diff --git a/firmware/qemu/src/bin/assert-eq.out b/firmware/qemu/src/bin/assert-eq.out
@@ -1,3 +1,4 @@
 ERROR panicked at 'assertion failed: `(left == right)`: dev'
- left: `41`
-right: `43`
+diff < left / right >
+<41
+>43
diff --git a/firmware/qemu/src/bin/bitflags.out b/firmware/qemu/src/bin/bitflags.out
@@ -1,12 +1,12 @@
-INFO Flags::empty(): FLAG_0
-INFO Flags::empty(): FLAG_0 (fmt::Debug)
-INFO Flags::all(): FLAG_1 | FLAG_2 | FLAG_7 | FLAG_7_COPY
-INFO Flags::all(): FLAG_1 | FLAG_2 | FLAG_7 | FLAG_7_COPY (fmt::Debug)
-INFO Flags::FLAG_1: FLAG_1
-INFO Flags::FLAG_1: FLAG_1 (fmt::Debug)
-INFO Flags::FLAG_7: FLAG_7 | FLAG_7_COPY
-INFO Flags::FLAG_7: FLAG_7 | FLAG_7_COPY (fmt::Debug)
-INFO LargeFlags::ALL: MSB | ALL | NON_LITERAL
-INFO LargeFlags::ALL: MSB | ALL | NON_LITERAL (fmt::Debug)
-INFO LargeFlags::empty(): (empty)
-INFO LargeFlags::empty(): (empty) (fmt::Debug)
+INFO  Flags::empty(): FLAG_0
+INFO  Flags::empty(): FLAG_0 (fmt::Debug)
+INFO  Flags::all(): FLAG_1 | FLAG_2 | FLAG_7 | FLAG_7_COPY
+INFO  Flags::all(): FLAG_1 | FLAG_2 | FLAG_7 | FLAG_7_COPY (fmt::Debug)
+INFO  Flags::FLAG_1: FLAG_1
+INFO  Flags::FLAG_1: FLAG_1 (fmt::Debug)
+INFO  Flags::FLAG_7: FLAG_7 | FLAG_7_COPY
+INFO  Flags::FLAG_7: FLAG_7 | FLAG_7_COPY (fmt::Debug)
+INFO  LargeFlags::ALL: MSB | ALL | NON_LITERAL
+INFO  LargeFlags::ALL: MSB | ALL | NON_LITERAL (fmt::Debug)
+INFO  LargeFlags::empty(): (empty)
+INFO  LargeFlags::empty(): (empty) (fmt::Debug)
diff --git a/firmware/qemu/src/bin/dbg.out b/firmware/qemu/src/bin/dbg.out
@@ -1,6 +1,6 @@
 TRACE x + 1 = 43
 TRACE x - 1 = 41
-INFO the answer is 41
+INFO  the answer is 41
 TRACE x - 2 = 40
 TRACE x + 2 = 44
 TRACE 

diff --git a/firmware/qemu/src/bin/hints.out b/firmware/qemu/src/bin/hints.out
@@ -1,76 +1,76 @@
-0.000000 INFO no hint 42
-0.000001 INFO hex     2a
-0.000002 INFO hex alt 0x2a
-0.000003 INFO HEX     2A
-0.000004 INFO HEX alt 0x2A
-0.000005 INFO octal   52
-0.000006 INFO octal alt 0o52
-0.000007 INFO binary  101010
-0.000008 INFO binary alt 0b101010
-0.000009 INFO ASCII   42
-0.000010 INFO Debug   42
-0.000011 INFO ----
-0.000012 INFO no-hint 42
-0.000013 INFO hex     2a
-0.000014 INFO hex alt 0x2a
-0.000015 INFO HEX     2A
-0.000016 INFO HEX alt 0x2A
-0.000017 INFO octal   52
-0.000018 INFO octal alt 0o52
-0.000019 INFO binary  101010
-0.000020 INFO binary alt 0b101010
-0.000021 INFO ASCII   42
-0.000022 INFO Debug   42
-0.000023 INFO ----
-0.000024 INFO no hint 42
-0.000025 INFO hex     2a
-0.000026 INFO hex alt 0x2a
-0.000027 INFO HEX     2A
-0.000028 INFO HEX alt 0x2A
-0.000029 INFO octal   52
-0.000030 INFO octal alt 0o52
-0.000031 INFO binary  101010
-0.000032 INFO binary alt 0b101010
-0.000033 INFO ASCII   42
-0.000034 INFO Debug   42
-0.000035 INFO ----
-0.000036 INFO S1 > S2 101010
-0.000037 INFO ----
-0.000038 INFO no hint [72, 101, 127, 108, 108, 111]
-0.000039 INFO hex     [48, 65, 7f, 6c, 6c, 6f]
-0.000040 INFO hex alt [0x48, 0x65, 0x7f, 0x6c, 0x6c, 0x6f]
-0.000041 INFO HEX     [48, 65, 7F, 6C, 6C, 6F]
-0.000042 INFO HEX alt [0x48, 0x65, 0x7F, 0x6C, 0x6C, 0x6F]
-0.000043 INFO octal   [110, 145, 177, 154, 154, 157]
-0.000044 INFO octal alt [0o110, 0o145, 0o177, 0o154, 0o154, 0o157]
-0.000045 INFO binary  [1001000, 1100101, 1111111, 1101100, 1101100, 1101111]
-0.000046 INFO binary alt [0b1001000, 0b1100101, 0b1111111, 0b1101100, 0b1101100, 0b1101111]
-0.000047 INFO ASCII   b"He\x7fllo"
-0.000048 INFO Debug   [72, 101, 127, 108, 108, 111]
-0.000049 INFO ----
-0.000050 INFO b"\x00\x01\x02\x03\x04\x05\x06\x07\x08\t\n\x0b\x0c\r\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f !\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~\x7f\x80\x81\x82\x83\x84\x85\x86\x87\x88\x89\x8a\x8b\x8c\x8d\x8e\x8f\x90\x91\x92\x93\x94\x95\x96\x97\x98\x99\x9a\x9b\x9c\x9d\x9e\x9f\xa0\xa1\xa2\xa3\xa4\xa5\xa6\xa7\xa8\xa9\xaa\xab\xac\xad\xae\xaf\xb0\xb1\xb2\xb3\xb4\xb5\xb6\xb7\xb8\xb9\xba\xbb\xbc\xbd\xbe\xbf\xc0\xc1\xc2\xc3\xc4\xc5\xc6\xc7\xc8\xc9\xca\xcb\xcc\xcd\xce\xcf\xd0\xd1\xd2\xd3\xd4\xd5\xd6\xd7\xd8\xd9\xda\xdb\xdc\xdd\xde\xdf\xe0\xe1\xe2\xe3\xe4\xe5\xe6\xe7\xe8\xe9\xea\xeb\xec\xed\xee\xef\xf0\xf1\xf2\xf3\xf4\xf5\xf6\xf7\xf8\xf9\xfa\xfb\xfc\xfd\xfe\xff"
-0.000051 INFO b"\x00\x01\x02\x03\x04\x05\x06\x07\x08\t\n\x0b\x0c\r\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f !\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~\x7f\x80\x81\x82\x83\x84\x85\x86\x87\x88\x89\x8a\x8b\x8c\x8d\x8e\x8f\x90\x91\x92\x93\x94\x95\x96\x97\x98\x99\x9a\x9b\x9c\x9d\x9e\x9f\xa0\xa1\xa2\xa3\xa4\xa5\xa6\xa7\xa8\xa9\xaa\xab\xac\xad\xae\xaf\xb0\xb1\xb2\xb3\xb4\xb5\xb6\xb7\xb8\xb9\xba\xbb\xbc\xbd\xbe\xbf\xc0\xc1\xc2\xc3\xc4\xc5\xc6\xc7\xc8\xc9\xca\xcb\xcc\xcd\xce\xcf\xd0\xd1\xd2\xd3\xd4\xd5\xd6\xd7\xd8\xd9\xda\xdb\xdc\xdd\xde\xdf\xe0\xe1\xe2\xe3\xe4\xe5\xe6\xe7\xe8\xe9\xea\xeb\xec\xed\xee\xef\xf0\xf1\xf2\xf3\xf4\xf5\xf6\xf7\xf8\xf9\xfa\xfb\xfc\xfd\xfe\xff"
-0.000052 INFO ----
-0.000053 INFO no hint Hello
-0.000054 INFO Debug   "Hello"
-0.000055 INFO no hint world
-0.000056 INFO Debug   "world"
-0.000057 INFO ----
-0.000058 INFO no hint 10
-0.000059 INFO hex     a
-0.000060 INFO hex     0xa
-0.000061 INFO HEX     A
-0.000062 INFO HEX     0xA
-0.000063 INFO octal   12
-0.000064 INFO octal   0o12
-0.000065 INFO binary  1010
-0.000066 INFO binary  0b1010
-0.000067 INFO ASCII   b"\n"
-0.000068 INFO Debug   10
-0.000069 INFO ISO8601 2021-04-20T09:23:44.804Z
-0.000070 INFO ISO8601 +53271-03-27T11:46:44Z
-0.000071 INFO Sec ms  1234.567
-0.000072 INFO Sec us  1.234567
-0.000073 INFO Time s  14:06:56:07
-0.000074 INFO Time ms 00:20:34.567
-0.000075 INFO Time us 00:00:01.234567
+0.000000 INFO  no hint 42
+0.000001 INFO  hex     2a
+0.000002 INFO  hex alt 0x2a
+0.000003 INFO  HEX     2A
+0.000004 INFO  HEX alt 0x2A
+0.000005 INFO  octal   52
+0.000006 INFO  octal alt 0o52
+0.000007 INFO  binary  101010
+0.000008 INFO  binary alt 0b101010
+0.000009 INFO  ASCII   42
+0.000010 INFO  Debug   42
+0.000011 INFO  ----
+0.000012 INFO  no-hint 42
+0.000013 INFO  hex     2a
+0.000014 INFO  hex alt 0x2a
+0.000015 INFO  HEX     2A
+0.000016 INFO  HEX alt 0x2A
+0.000017 INFO  octal   52
+0.000018 INFO  octal alt 0o52
+0.000019 INFO  binary  101010
+0.000020 INFO  binary alt 0b101010
+0.000021 INFO  ASCII   42
+0.000022 INFO  Debug   42
+0.000023 INFO  ----
+0.000024 INFO  no hint 42
+0.000025 INFO  hex     2a
+0.000026 INFO  hex alt 0x2a
+0.000027 INFO  HEX     2A
+0.000028 INFO  HEX alt 0x2A
+0.000029 INFO  octal   52
+0.000030 INFO  octal alt 0o52
+0.000031 INFO  binary  101010
+0.000032 INFO  binary alt 0b101010
+0.000033 INFO  ASCII   42
+0.000034 INFO  Debug   42
+0.000035 INFO  ----
+0.000036 INFO  S1 > S2 101010
+0.000037 INFO  ----
+0.000038 INFO  no hint [72, 101, 127, 108, 108, 111]
+0.000039 INFO  hex     [48, 65, 7f, 6c, 6c, 6f]
+0.000040 INFO  hex alt [0x48, 0x65, 0x7f, 0x6c, 0x6c, 0x6f]
+0.000041 INFO  HEX     [48, 65, 7F, 6C, 6C, 6F]
+0.000042 INFO  HEX alt [0x48, 0x65, 0x7F, 0x6C, 0x6C, 0x6F]
+0.000043 INFO  octal   [110, 145, 177, 154, 154, 157]
+0.000044 INFO  octal alt [0o110, 0o145, 0o177, 0o154, 0o154, 0o157]
+0.000045 INFO  binary  [1001000, 1100101, 1111111, 1101100, 1101100, 1101111]
+0.000046 INFO  binary alt [0b1001000, 0b1100101, 0b1111111, 0b1101100, 0b1101100, 0b1101111]
+0.000047 INFO  ASCII   b"He\x7fllo"
+0.000048 INFO  Debug   [72, 101, 127, 108, 108, 111]
+0.000049 INFO  ----
+0.000050 INFO  b"\x00\x01\x02\x03\x04\x05\x06\x07\x08\t\n\x0b\x0c\r\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f !\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~\x7f\x80\x81\x82\x83\x84\x85\x86\x87\x88\x89\x8a\x8b\x8c\x8d\x8e\x8f\x90\x91\x92\x93\x94\x95\x96\x97\x98\x99\x9a\x9b\x9c\x9d\x9e\x9f\xa0\xa1\xa2\xa3\xa4\xa5\xa6\xa7\xa8\xa9\xaa\xab\xac\xad\xae\xaf\xb0\xb1\xb2\xb3\xb4\xb5\xb6\xb7\xb8\xb9\xba\xbb\xbc\xbd\xbe\xbf\xc0\xc1\xc2\xc3\xc4\xc5\xc6\xc7\xc8\xc9\xca\xcb\xcc\xcd\xce\xcf\xd0\xd1\xd2\xd3\xd4\xd5\xd6\xd7\xd8\xd9\xda\xdb\xdc\xdd\xde\xdf\xe0\xe1\xe2\xe3\xe4\xe5\xe6\xe7\xe8\xe9\xea\xeb\xec\xed\xee\xef\xf0\xf1\xf2\xf3\xf4\xf5\xf6\xf7\xf8\xf9\xfa\xfb\xfc\xfd\xfe\xff"
+0.000051 INFO  b"\x00\x01\x02\x03\x04\x05\x06\x07\x08\t\n\x0b\x0c\r\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f !\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~\x7f\x80\x81\x82\x83\x84\x85\x86\x87\x88\x89\x8a\x8b\x8c\x8d\x8e\x8f\x90\x91\x92\x93\x94\x95\x96\x97\x98\x99\x9a\x9b\x9c\x9d\x9e\x9f\xa0\xa1\xa2\xa3\xa4\xa5\xa6\xa7\xa8\xa9\xaa\xab\xac\xad\xae\xaf\xb0\xb1\xb2\xb3\xb4\xb5\xb6\xb7\xb8\xb9\xba\xbb\xbc\xbd\xbe\xbf\xc0\xc1\xc2\xc3\xc4\xc5\xc6\xc7\xc8\xc9\xca\xcb\xcc\xcd\xce\xcf\xd0\xd1\xd2\xd3\xd4\xd5\xd6\xd7\xd8\xd9\xda\xdb\xdc\xdd\xde\xdf\xe0\xe1\xe2\xe3\xe4\xe5\xe6\xe7\xe8\xe9\xea\xeb\xec\xed\xee\xef\xf0\xf1\xf2\xf3\xf4\xf5\xf6\xf7\xf8\xf9\xfa\xfb\xfc\xfd\xfe\xff"
+0.000052 INFO  ----
+0.000053 INFO  no hint Hello
+0.000054 INFO  Debug   "Hello"
+0.000055 INFO  no hint world
+0.000056 INFO  Debug   "world"
+0.000057 INFO  ----
+0.000058 INFO  no hint 10
+0.000059 INFO  hex     a
+0.000060 INFO  hex     0xa
+0.000061 INFO  HEX     A
+0.000062 INFO  HEX     0xA
+0.000063 INFO  octal   12
+0.000064 INFO  octal   0o12
+0.000065 INFO  binary  1010
+0.000066 INFO  binary  0b1010
+0.000067 INFO  ASCII   b"\n"
+0.000068 INFO  Debug   10
+0.000069 INFO  ISO8601 2021-04-20T09:23:44.804Z
+0.000070 INFO  ISO8601 +53271-03-27T11:46:44Z
+0.000071 INFO  Sec ms  1234.567
+0.000072 INFO  Sec us  1.234567
+0.000073 INFO  Time s  14:06:56:07
+0.000074 INFO  Time ms 00:20:34.567
+0.000075 INFO  Time us 00:00:01.234567
diff --git a/firmware/qemu/src/bin/hints_inner.out b/firmware/qemu/src/bin/hints_inner.out
@@ -1,10 +1,10 @@
-0.000000 INFO S1 { x: "hi", y: 0x2a }
-0.000001 INFO S2 { x: 0x2a }
-0.000002 WARN Debug hint: S { x: "hello", y: 512 }
-0.000003 WARN    no hint: S { x: "hello", y: 1024 }
-0.000004 INFO S2 { s: S1 { x: 0b100, y: 12 }, z: 20 }
-0.000005 INFO S2 { s: S1 { x: 0b100, y: 12 }, z: 20 }
-0.000006 INFO S2 { s: S1 { x: 0b100, y: 12 }, z: 0x14 }
-0.000007 INFO S2 { s: S1 { x: 0b100, y: 12 }, z: 0b10100 }
-0.000008 INFO S1 { x: "hi", y: 42 }
-0.000009 INFO S1 { x: "hi", y: 0x2a }
+0.000000 INFO  S1 { x: "hi", y: 0x2a }
+0.000001 INFO  S2 { x: 0x2a }
+0.000002 WARN  Debug hint: S { x: "hello", y: 512 }
+0.000003 WARN     no hint: S { x: "hello", y: 1024 }
+0.000004 INFO  S2 { s: S1 { x: 0b100, y: 12 }, z: 20 }
+0.000005 INFO  S2 { s: S1 { x: 0b100, y: 12 }, z: 20 }
+0.000006 INFO  S2 { s: S1 { x: 0b100, y: 12 }, z: 0x14 }
+0.000007 INFO  S2 { s: S1 { x: 0b100, y: 12 }, z: 0b10100 }
+0.000008 INFO  S1 { x: "hi", y: 42 }
+0.000009 INFO  S1 { x: "hi", y: 0x2a }