acpi: DSDT/SSDT runtime patching

Here's an updated revision of acpi runtime patching patchset. As promised, this revision replaces the hardcoded offsets in the ssdt_proc table with ones generated dynamically from the mixed asl/aml listing.

Changes in v3:
- change ssdt generation code to get rid of hardcoded offsets
- enhancements to acpi_extract: add more extract methods ACPI_EXTRACT_NAME_WORD_CONST - extract a Word Const object from Name() ACPI_EXTRACT_NAME_BYTE_CONST - extract a Byte Const object from Name() ACPI_EXTRACT_PROCESSOR_START - start of Processor() block ACPI_EXTRACT_PROCESSOR_STRING - extract a NameString from Processor() ACPI_EXTRACT_PROCESSOR_END - offset at last byte of Processor() + 1

Changes in v2:
- tools rewritten in python
- Original ASL retains _EJ0 methods, BIOS patches that to EJ0_
- generic ACP_EXTRACT infrastructure that can match Method and Name Operators
- instead of matching specific method name, insert tags in original DSL source and match that to AML

-----

Here's a bug: guest thinks it can eject VGA device and ISA bridge.

[root@dhcp74-172 ~]#lspci
00:00.0 Host bridge: Intel Corporation 440FX - 82441FX PMC [Natoma] (rev 02) 00:01.0 ISA bridge: Intel Corporation 82371SB PIIX3 ISA [Natoma/Triton II] 00:01.1 IDE interface: Intel Corporation 82371SB PIIX3 IDE [Natoma/Triton II] 00:01.3 Bridge: Intel Corporation 82371AB/EB/MB PIIX4 ACPI (rev 03)
00:02.0 VGA compatible controller: Cirrus Logic GD 5446
00:03.0 PCI bridge: Red Hat, Inc. Device 0001
00:04.0 Ethernet controller: Qumranet, Inc. Virtio network device
00:05.0 SCSI storage controller: Qumranet, Inc. Virtio block device
01:00.0 Ethernet controller: Intel Corporation 82540EM Gigabit Ethernet Controller (rev 03)

[root@dhcp74-172 ~]# ls /sys/bus/pci/slots/1/
adapter address attention latch module power
[root@dhcp74-172 ~]# ls /sys/bus/pci/slots/2/
adapter address attention latch module power

[root@dhcp74-172 ~]# echo 0 > /sys/bus/pci/slots/2/power
[root@dhcp74-172 ~]# lspci
00:00.0 Host bridge: Intel Corporation 440FX - 82441FX PMC [Natoma] (rev 02) 00:01.0 ISA bridge: Intel Corporation 82371SB PIIX3 ISA [Natoma/Triton II] 00:01.1 IDE interface: Intel Corporation 82371SB PIIX3 IDE [Natoma/Triton II] 00:01.3 Bridge: Intel Corporation 82371AB/EB/MB PIIX4 ACPI (rev 03)
00:03.0 PCI bridge: Red Hat, Inc. Device 0001
00:04.0 Ethernet controller: Qumranet, Inc. Virtio network device
00:05.0 SCSI storage controller: Qumranet, Inc. Virtio block device
01:00.0 Ethernet controller: Intel Corporation 82540EM Gigabit Ethernet Controller (rev 03)

This is wrong because slots 1 and 2 are marked as not hotpluggable in qemu.

The reason is that our acpi tables declare both _RMV with value 0, and _EJ0 method for these slots. What happens in this case is undocumented by ACPI spec, so linux ignores _RMV, and windows seems to ignore _EJ0.

The correct way to suppress hotplug is not to have _EJ0, so this is what this patch does: it probes PIIX and modifies DSDT to match.

With these patches applied, we get:

[root@dhcp74-172 ~]# ls /sys/bus/pci/slots/1/
address
[root@dhcp74-172 ~]# ls /sys/bus/pci/slots/2/
address

Michael S. Tsirkin (4):
acpi: generate and parse mixed asl/aml listing
acpi: EJ0 method name patching
acpi: remove _RMV
acpi: automatically generated ssdt proc

 Makefile                         |   12 +-
 src/acpi-dsdt.dsl                |   96 +++++--------
 src/acpi.c                       |   64 ++++++---
 src/ssdt-proc.dsl                |   19 +--
 tools/acpi_extract.py            |  278 ++++++++++++++++++++++++++++++++++++++
 tools/acpi_extract_preprocess.py |   37 +++++
 6 files changed, 411 insertions(+), 95 deletions(-)
 create mode 100755 tools/acpi_extract.py
 create mode 100755 tools/acpi_extract_preprocess.py

1.7.5.53.gc233e

Use iasl -l flag to produce a mixed listing, where a source line is followed by matching AML.

Add a tool tools/acpi_extract.py to process this listing. The tool looks for ACPI_EXTRACT tags in the ASL source and outputs matching AML offsets in an array.

To make these directives pass through ASL without affecting AML, and to make it possible to match AML to source exactly, add a preprocessing stage, which prepares input for iasl, and puts each ACPI_EXTRACT tag within a comment,
on a line by itself.

---
 Makefile                         |   10 +-
 tools/acpi_extract.py            |  278 ++++++++++++++++++++++++++++++++++++++
 tools/acpi_extract_preprocess.py |   37 +++++
 3 files changed, 321 insertions(+), 4 deletions(-)
 create mode 100755 tools/acpi_extract.py
 create mode 100755 tools/acpi_extract_preprocess.py

index 109091b..541b080 100644
@@ -192,11 +192,13 @@ $(OUT)vgabios.bin: $(OUT)vgabios.bin.raw tools/buildrom.py
 	$(Q)./tools/buildrom.py $< $@
 
 ####### dsdt build rules
-src/%.hex: src/%.dsl
+src/%.hex: src/%.dsl ./tools/acpi_extract_preprocess.py ./tools/acpi_extract.py
 	@echo "Compiling DSDT"
-	$(Q)cpp -P $< > $(OUT)$*.dsl.i
-	$(Q)iasl -tc -p $(OUT)$* $(OUT)$*.dsl.i
-	$(Q)cp $(OUT)$*.hex $@
+	$(Q)cpp -P $< > $(OUT)$*.dsl.i.orig
+	$(Q)./tools/acpi_extract_preprocess.py $(OUT)$*.dsl.i.orig > $(OUT)$*.dsl.i
+	$(Q)iasl -l -tc -p $(OUT)$* $(OUT)$*.dsl.i
+	$(Q)./tools/acpi_extract.py $(OUT)$*.lst > $(OUT)$*.off
+	$(Q)cat $(OUT)$*.hex $(OUT)$*.off > $@
 
 $(OUT)ccode32flat.o: src/acpi-dsdt.hex
 

new file mode 100755
index 0000000..2eb9e1d
@@ -0,0 +1,37 @@
+#!/usr/bin/python
+# Read a preprocessed ASL listing and put each ACPI_EXTRACT
+# directive in a comment, to make iasl skip it.
+# We also put each directive on a new line, the machinery
+# in tools/acpi_extract.py requires this.
+
+import re;
+import sys;
+import fileinput;
+
+def die(diag):
+    sys.stderr.write("Error: %s\n" % (diag))
+    sys.exit(1)
+
+# Note: () around pattern make split return matched string as part of list
+psplit = re.compile(r''' (
+                          \b # At word boundary
+                          ACPI_EXTRACT_\w+ # directive
+                          \s+ # some whitespace
+                          \w+ # array name
+                         )''', re.VERBOSE);
+
+lineno = 0
+for line in fileinput.input():
+    # line number and debug string to output in case of errors
+    lineno = lineno + 1
+    debug = "input line %d: %s" % (lineno, line.rstrip())
+
+    s = psplit.split(line);
+    # The way split works, each odd item is the matching ACPI_EXTRACT directive.
+    # Put each in a comment, and on a line by itself.
+    for i in range(len(s)):
+        if (i % 2):
+            sys.stdout.write("\n/* %s */\n" % s[i])
+        else:
+            sys.stdout.write(s[i])
+

1.7.5.53.gc233e

Modify ACPI to only supply _EJ0 methods for PCI
slots that support hotplug.

This is done by runtime patching:
- Instrument ASL code with ACPI_EXTRACT directives tagging _EJ0 and _ADR fields.
- At compile time, tools/acpi_extract.py looks for these methods in ASL source finds the matching AML, and stores the offsets of these methods in tables named aml_ej0_name and aml_adr_dword.
- At run time, go over aml_ej0_name, use aml_adr_dword to get slot information and check which slots
support hotplug.

If hotplug is disabled, we patch the _EJ0 NameString in ACPI table, replacing _EJ0 with EJ0_.

Note that this has the same checksum, but
is ignored by OSPM.

Note: the method used is robust in that we don't need
to change any offsets manually in case of ASL code changes. As all parsing is done at compile time, any unexpected input causes build failure, not a runtime failure.

---
 src/acpi-dsdt.dsl |   47 ++++++++++++++++++++++++++++++++++++++---------
 src/acpi.c        |   31 +++++++++++++++++++++++++++++++
 2 files changed, 69 insertions(+), 9 deletions(-)

index 08412e2..440e315 100644
@@ -16,6 +16,30 @@
  * License along with this library; if not, write to the Free Software
  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  */
+
+/*
+Documentation of ACPI_EXTRACT_* directive tags:
+
+These directive tags are processed by tools/acpi_extract.py
+to output offset information from AML for BIOS runtime table generation.
+Each directive is of the form:
+ACPI_EXTRACT_<TYPE> <array_name> <Operator> (...)
+and causes the extractor to create an array
+named <array_name> with offset, in the generated AML,
+of an object of a given type from the following <Operator>.
+
+A directive and array name must fit on a single code line.
+
+Object type in AML is verified, a mismatch causes a build failure.
+
+Directives and operators currently supported are:
+ACPI_EXTRACT_NAME_DWORD_CONST - extract a Dword Const object from Name()
+ACPI_EXTRACT_METHOD_STRING - extract a NameString from Method()
+ACPI_EXTRACT_NAME_STRING - extract a NameString from Name()
+
+ACPI_EXTRACT is not allowed anywhere else in code, except in comments.
+*/
+
 DefinitionBlock (
     "acpi-dsdt.aml",    // Output Filename
     "DSDT",             // Signature

@@ -127,15 +151,20 @@ DefinitionBlock (
             {
                 PCRM, 32,
             }
-
-#define hotplug_slot(name, nr) \
-            Device (S##name) {                    \
-               Name (_ADR, nr##0000)              \
-               Method (_EJ0,1) {                  \
-                    Store(ShiftLeft(1, nr), B0EJ) \
-                    Return (0x0)                  \
-               }                                  \
-               Name (_SUN, name)                  \
+            // Method _EJ0 can be patched by BIOS to EJ0_
+            // at runtime, if the slot is detected to not support hotplug.
+            // Extract the offset of the address dword and the
+            // _EJ0 name to allow this patching.
+#define hotplug_slot(name, nr)                                    \
+            Device (S##name) {                                    \
+                ACPI_EXTRACT_NAME_DWORD_CONST aml_adr_dword       \
+                Name (_ADR, nr##0000)                             \
+                ACPI_EXTRACT_METHOD_STRING aml_ej0_name           \
+                Method  (_EJ0, 1) {                               \
+                    Store(ShiftLeft(1, nr), B0EJ)                 \
+                    Return (0x0)                                  \
+               }                                                  \
+               Name (_SUN, name)                                  \
             }
 
 	    hotplug_slot(1, 0x0001)

index 6bb6ff6..f65f974 100644
@@ -198,6 +198,8 @@ struct srat_memory_affinity
     u32    reserved3[2];
 } PACKED;
 
+#define PCI_RMV_BASE 0xae0c
+
 #include "acpi-dsdt.hex"
 
 static void

@@ -237,12 +239,16 @@ static const struct pci_device_id fadt_init_tbl[] = {
     PCI_DEVICE_END
 };
 
+extern void link_time_assertion(void);
+
 static void *
 build_fadt(struct pci_device *pci)
 {
     struct fadt_descriptor_rev1 *fadt = malloc_high(sizeof(*fadt));
     struct facs_descriptor_rev1 *facs = memalign_high(64, sizeof(*facs));
     void *dsdt = malloc_high(sizeof(AmlCode));
+    u32 rmvc_pcrm;
+    int i;
 
     if (!fadt || !facs || !dsdt) {
         warn_noalloc();

@@ -257,6 +263,25 @@ build_fadt(struct pci_device *pci)
     /* DSDT */
     memcpy(dsdt, AmlCode, sizeof(AmlCode));
 
+    /* Runtime patching of EJ0: to disable hotplug for a slot,
+     * replace the method name: _EJ0 by EJ0_. */
+    if (ARRAY_SIZE(aml_ej0_name) != ARRAY_SIZE(aml_adr_dword)) {
+        link_time_assertion();
+    }
+    rmvc_pcrm = inl(PCI_RMV_BASE);
+    for (i = 0; i < ARRAY_SIZE(aml_ej0_name); ++i) {
+        /* Slot is in byte 2 in _ADR */
+        u8 slot = AmlCode[aml_adr_dword[i] + 2] & 0x1F;
+	/* Sanity check */
+        if (memcmp(AmlCode + aml_ej0_name[i], "_EJ0", 4)) {
+            warn_internalerror();
+            goto error;
+        }
+        if (!(rmvc_pcrm & (0x1 << slot))) {
+            memcpy(dsdt + aml_ej0_name[i], "EJ0_", 4);
+        }
+    }
+
     /* FADT */
     memset(fadt, 0, sizeof(*fadt));
     fadt->firmware_ctrl = cpu_to_le32((u32)facs);

@@ -281,6 +306,12 @@ build_fadt(struct pci_device *pci)
     build_header((void*)fadt, FACP_SIGNATURE, sizeof(*fadt), 1);
 
     return fadt;
+
+error:
+    free(fadt);
+    free(facs);
+    free(dsdt);
+    return NULL;
 }
 
 static void*

1.7.5.53.gc233e

The macro gen_pci_device is used to add _RMV method to a slot device so it is no longer needed:
presence of _EJ0 now indicates that the slot is ejectable. It is also placing two devices with the same _ADR on the same bus, which isn't defined by the ACPI spec. So let's remove it.

---
 src/acpi-dsdt.dsl |   49 -------------------------------------------------
 1 files changed, 0 insertions(+), 49 deletions(-)

index 440e315..055202b 100644
@@ -145,12 +145,6 @@ DefinitionBlock (
             {
                 B0EJ, 32,
             }
-
-            OperationRegion(RMVC, SystemIO, 0xae0c, 0x04)
-            Field(RMVC, DWordAcc, NoLock, WriteAsZeros)
-            {
-                PCRM, 32,
-            }
             // Method _EJ0 can be patched by BIOS to EJ0_
             // at runtime, if the slot is detected to not support hotplug.
             // Extract the offset of the address dword and the

@@ -488,49 +482,6 @@ DefinitionBlock (
 		DRSJ, 32
 	    }
 	}
-
-#define gen_pci_device(name, nr)                                \
-        Device(SL##name) {                                      \
-            Name (_ADR, nr##0000)                               \
-            Method (_RMV) {                                     \
-                If (And(\_SB.PCI0.PCRM, ShiftLeft(1, nr))) {    \
-                    Return (0x1)                                \
-                }                                               \
-                Return (0x0)                                    \
-            }                                                   \
-            Name (_SUN, name)                                   \
-        }
-
-        /* VGA (slot 1) and ISA bus (slot 2) defined above */
-	gen_pci_device(3, 0x0003)
-	gen_pci_device(4, 0x0004)
-	gen_pci_device(5, 0x0005)
-	gen_pci_device(6, 0x0006)
-	gen_pci_device(7, 0x0007)
-	gen_pci_device(8, 0x0008)
-	gen_pci_device(9, 0x0009)
-	gen_pci_device(10, 0x000a)
-	gen_pci_device(11, 0x000b)
-	gen_pci_device(12, 0x000c)
-	gen_pci_device(13, 0x000d)
-	gen_pci_device(14, 0x000e)
-	gen_pci_device(15, 0x000f)
-	gen_pci_device(16, 0x0010)
-	gen_pci_device(17, 0x0011)
-	gen_pci_device(18, 0x0012)
-	gen_pci_device(19, 0x0013)
-	gen_pci_device(20, 0x0014)
-	gen_pci_device(21, 0x0015)
-	gen_pci_device(22, 0x0016)
-	gen_pci_device(23, 0x0017)
-	gen_pci_device(24, 0x0018)
-	gen_pci_device(25, 0x0019)
-	gen_pci_device(26, 0x001a)
-	gen_pci_device(27, 0x001b)
-	gen_pci_device(28, 0x001c)
-	gen_pci_device(29, 0x001d)
-	gen_pci_device(30, 0x001e)
-	gen_pci_device(31, 0x001f)
     }
 
     /* PCI IRQs */

1.7.5.53.gc233e

Get rid of manually cut and pasted ssdt_proc,
use ssdt compiled by iasl and offsets extracted
by acpi_extract instead.

---
 Makefile          |    2 +-
 src/acpi.c        |   33 +++++++++++++--------------------
 src/ssdt-proc.dsl |   19 +++++++------------
 3 files changed, 21 insertions(+), 33 deletions(-)

index 541b080..fee68aa 100644
@@ -200,7 +200,7 @@ src/%.hex: src/%.dsl ./tools/acpi_extract_preprocess.py ./tools/acpi_extract.py
 	$(Q)./tools/acpi_extract.py $(OUT)$*.lst > $(OUT)$*.off
 	$(Q)cat $(OUT)$*.hex $(OUT)$*.off > $@
 
-$(OUT)ccode32flat.o: src/acpi-dsdt.hex
+$(OUT)ccode32flat.o: src/acpi-dsdt.hex src/ssdt-proc.hex
 
 ####### Kconfig rules
 export HOSTCC             := $(CC)

index f65f974..cf60257 100644
@@ -398,23 +398,16 @@ encodeLen(u8 *ssdt_ptr, int length, int bytes)
     return ssdt_ptr + bytes;
 }
 
-// AML Processor() object.  See src/ssdt-proc.dsl for info.
-static unsigned char ssdt_proc[] = {
-    0x5b,0x83,0x42,0x05,0x43,0x50,0x41,0x41,
-    0xaa,0x10,0xb0,0x00,0x00,0x06,0x08,0x49,
-    0x44,0x5f,0x5f,0x0a,0xaa,0x08,0x5f,0x48,
-    0x49,0x44,0x0d,0x41,0x43,0x50,0x49,0x30,
-    0x30,0x30,0x37,0x00,0x14,0x0f,0x5f,0x4d,
-    0x41,0x54,0x00,0xa4,0x43,0x50,0x4d,0x41,
-    0x49,0x44,0x5f,0x5f,0x14,0x0f,0x5f,0x53,
-    0x54,0x41,0x00,0xa4,0x43,0x50,0x53,0x54,
-    0x49,0x44,0x5f,0x5f,0x14,0x0f,0x5f,0x45,
-    0x4a,0x30,0x01,0x43,0x50,0x45,0x4a,0x49,
-    0x44,0x5f,0x5f,0x68
-};
-#define SD_OFFSET_CPUHEX 6
-#define SD_OFFSET_CPUID1 8
-#define SD_OFFSET_CPUID2 20
+#define AmlCode static ssdp_proc_aml
+#include "ssdt-proc.hex"
+#undef AmlCode
+
+/* 0x5B 0x83 ProcessorOp PkgLength NameString ProcID */
+#define SD_OFFSET_CPUHEX (*ssdt_proc_name - *ssdt_proc_start + 2)
+#define SD_OFFSET_CPUID1 (*ssdt_proc_name - *ssdt_proc_start + 4)
+#define SD_OFFSET_CPUID2 (*ssdt_proc_id - *ssdt_proc_start)
+#define SD_SIZEOF (*ssdt_proc_end - *ssdt_proc_start)
+#define SD_PROC (ssdp_proc_aml + *ssdt_proc_start)
 
 #define SSDT_SIGNATURE 0x54445353 // SSDT
 static void*

@@ -423,7 +416,7 @@ build_ssdt(void)
     int acpi_cpus = MaxCountCPUs > 0xff ? 0xff : MaxCountCPUs;
     // length = ScopeOp + procs + NTYF method + CPON package
     int length = ((1+3+4)
-                  + (acpi_cpus * sizeof(ssdt_proc))
+                  + (acpi_cpus * SD_SIZEOF)
                   + (1+2+5+(12*acpi_cpus))
                   + (6+2+1+(1*acpi_cpus)));
     u8 *ssdt = malloc_high(sizeof(struct acpi_table_header) + length);

@@ -444,12 +437,12 @@ build_ssdt(void)
     // build Processor object for each processor
     int i;
     for (i=0; i<acpi_cpus; i++) {
-        memcpy(ssdt_ptr, ssdt_proc, sizeof(ssdt_proc));
+        memcpy(ssdt_ptr, SD_PROC, SD_SIZEOF);
         ssdt_ptr[SD_OFFSET_CPUHEX] = getHex(i >> 4);
         ssdt_ptr[SD_OFFSET_CPUHEX+1] = getHex(i);
         ssdt_ptr[SD_OFFSET_CPUID1] = i;
         ssdt_ptr[SD_OFFSET_CPUID2] = i;
-        ssdt_ptr += sizeof(ssdt_proc);
+        ssdt_ptr += SD_SIZEOF;
     }
 
     // build "Method(NTFY, 2) {If (LEqual(Arg0, 0x00)) {Notify(CP00, Arg1)} ...}"

index 358afa8..a461636 100644
@@ -1,16 +1,9 @@
-/* This file is the basis for the ssdt_proc[] variable in src/acpi.c.
+/* This file is the basis for the ssdt table generated in src/acpi.c.
  * It defines the contents of the per-cpu Processor() object.  At
  * runtime, a dynamically generated SSDT will contain one copy of this
  * AML snippet for every possible cpu in the system.  The objects will
  * be placed in the \_SB_ namespace.
  *
- * To generate a new ssdt_proc[], run the commands:
- *   cpp -P src/ssdt-proc.dsl > out/ssdt-proc.dsl.i
- *   iasl -ta -p out/ssdt-proc out/ssdt-proc.dsl.i
- *   tail -c +37 < out/ssdt-proc.aml | hexdump -e '"    " 8/1 "0x%02x," "\n"'
- * and then cut-and-paste the output into the src/acpi.c ssdt_proc[]
- * array.
- *
  * In addition to the aml code generated from this file, the
  * src/acpi.c file creates a NTFY method with an entry for each cpu:
  *     Method(NTFY, 2) {

@@ -22,13 +15,15 @@
  *     Name(CPON, Package() { One, One, ..., Zero, Zero, ... })
  */
 DefinitionBlock ("ssdt-proc.aml", "SSDT", 0x01, "BXPC", "BXSSDT", 0x1)
-/*  v------------------ DO NOT EDIT ------------------v */
 {
+    ACPI_EXTRACT_PROCESSOR_START ssdt_proc_start
+    ACPI_EXTRACT_PROCESSOR_END ssdt_proc_end
+    ACPI_EXTRACT_PROCESSOR_STRING ssdt_proc_name
     Processor (CPAA, 0xAA, 0x0000b010, 0x06) {
+        ACPI_EXTRACT_NAME_BYTE_CONST ssdt_proc_id
         Name (ID, 0xAA)
-/*  ^------------------ DO NOT EDIT ------------------^
- *
- * The src/acpi.c code requires the above layout so that it can update
+/*
+ * The src/acpi.c code requires the above ACP_EXTRACT tags so that it can update
  * CPAA and 0xAA with the appropriate CPU id (see
  * SD_OFFSET_CPUHEX/CPUID1/CPUID2).  Don't change the above without
  * also updating the C code.

1.7.5.53.gc233e

Thanks - I like the idea of auto-generating the offsets.

[...]

[...]

    ACPI_EXTRACT ssdt_proc_obj
    Processor (CPAA, 0xAA, 0x0000b010, 0x06) {

    ACPI_EXTRACT hotplug_obj
    Device (SL00) {
        ACPI_EXTRACT_NAME_DWORD_CONST hotplog_id
        Name (ID, 0xAABBCCDD)
        Name (_ADR, ID)
        Method (_EJ0, 1) { Return(PCEJ(ID)) }
        Name (_SUN, ID)
    }

That would mean we will output hex as well, ignore the hex produced by iasl. Sure, I can do that. Another benefit would be that we can skip the ssdt preamble generated by iasl in the hex we output.

I considered this, sure. We could parse AML to figure out what is the object type we are trying to look up.

However I decided sanity-checking that we get the right type of object in AML is better. This way if iasl output format breaks
we will have a better chance to detect that.
Makes sense?

Also this can not be as generic as it seems: each type of object in AML bytecode is encoded slightly differently. So we would still have types of objects we support and types of object we don't.

What is the param offset here?

I really think multiple arrays are better so we don't waste memory on fields that we don't need and alignment.
I also dislike hardcoding field names. With a struct, if you want to know where did 'param' come from you must read python. My way, all names come from DSL source.

Hmm, not sure I understand why. Could you explain pls?

This assumes all devices are the same. But unfortunately this will not work for other devices such as VGA.

Yes. I guess one could do ACPI_EXTRACT_PROCESSOR for the sanity check.

Yes.

The location of the first byte of the parameters (the same as you had for ssdt_proc_name). Normally, AML objects take the form: <id> <length> <fixed params> <variable param list>. The <length> is itself of variable length, so passing in the start of the fixed parameters would make manipulating the results easier.

Sure:

- The DSDT is big and has several cross-functional users. Patching up the DSDT for hotplug when the DSDT also has unrelated stuff (eg, mouse) seems ugly.

- The PCI hotplug stuff is generating a whole bunch of devices and the dynamic code is effectively disabling the unwanted ones. It seems nicer to dynamically generate the desired entries instead of bulk generating and dynamically blanking.

- The CPU hotplug has similar requirements, but is implemented differently - it generates the CPU objects dynamically. It's not desirable to bulk generate the CPU objects and "blank" them dynamically, because 255 CPU objects would noticeably increase SeaBIOS' static size.

- Some time back there were patches floating around to pass the DSDT into SeaBIOS via fw_cfg interface. Those patches never made it in (I forget why), but the basic functionality seemed sound. Patching the DSDT in SeaBIOS would seem to eliminate that possibility.

None of these would be road-blocks. However, they make me want to consider other approaches.

The VGA device can't be hotplugged, so I don't see why that would be an issue.

-Kevin

Maybe a bit late comment.
At that time, the patch for qemu-side was NOT merged.
Right now it is merged into the qemu upstream as 104bf02eb50e080ac9d0de5905f80f9a09730154
(It took very long time to draw attention from the maintainers. sigh.)

Keven, if you like, I'm willing to rebase/resend it.

thanks,

yamahata

Sure - if the qemu part is upstream, send the patch again.

-Kevin

So if we had the hotplug stuff in a separate ssdt, and patched that in the same way my patches do, this seems to address 3 comments otu of 4 (all except the second one).

We'll want to do something else for a bridge, but for now this seems a sane compromise?

MST

FYI - I pushed the "ACPI DSDT simplifications" series and patch 1 and 4 from this series.

-Kevin