On 11/02/2016 12:24 AM, Igor Mammedov wrote:
On Sat, 29 Oct 2016 00:35:39 +0800
Xiao Guangrong <guangrong.xiao@xxxxxxxxxxxxxxx> wrote:
_FIT is required for hotplug support, guest will inquire the updated
device info from it if a hotplug event is received
As FIT buffer is not completely mapped into guest address space, so a
new function, Read FIT whose UUID is UUID
648B9CF2-CDA1-4312-8AD9-49C4AF32BD62, handle 0x10000, function index
is 0x1, is reserved by QEMU to read the piece of FIT buffer. The buffer
is concatenated before _FIT return
Refer to docs/specs/acpi-nvdimm.txt for detailed design
Signed-off-by: Xiao Guangrong <guangrong.xiao@xxxxxxxxxxxxxxx>
---
docs/specs/acpi_nvdimm.txt | 58 ++++++++++++-
hw/acpi/nvdimm.c | 204 ++++++++++++++++++++++++++++++++++++++++++++-
2 files changed, 257 insertions(+), 5 deletions(-)
diff --git a/docs/specs/acpi_nvdimm.txt b/docs/specs/acpi_nvdimm.txt
index 0fdd251..4aa5e3d 100644
--- a/docs/specs/acpi_nvdimm.txt
+++ b/docs/specs/acpi_nvdimm.txt
@@ -127,6 +127,58 @@ _DSM process diagram:
| result from the page | | |
+--------------------------+ +--------------+
- _FIT implementation
- -------------------
- TODO (will fill it when nvdimm hotplug is introduced)
+Device Handle Reservation
+-------------------------
+As we mentioned above, byte 0 ~ byte 3 in the DSM memory save NVDIMM device
+handle. The handle is completely QEMU internal thing, the values in range
+[0, 0xFFFF] indicate nvdimm device (O means nvdimm root device named NVDR),
+other values are reserved by other purpose.
+
+Current reserved handle:
+0x10000 is reserved for QEMU internal DSM function called on the root
+device.
Above part should go to section where 'handle' is defined, i.e. earlier in the file:
ACPI writes _DSM Input Data (based on the offset in the page):
[0x0 - 0x3]: 4 bytes, NVDIMM Device Handle, 0 is reserved for NVDIMM
Root device.
Okay.
+QEMU internal use only _DSM function
+------------------------------------
+UUID, 648B9CF2-CDA1-4312-8AD9-49C4AF32BD62, is reserved for QEMU internal
+DSM function.
+
+There is the function introduced by QEMU and only used by QEMU internal.
+
+1) Read FIT
UUID 648B9CF2-CDA1-4312-8AD9-49C4AF32BD62 is reserved for Read_FIT DSM function
(private QEMU function)
okay.
+ As we only reserved one page for NVDIMM ACPI it is impossible to map the
+ whole FIT data to guest's address space. This function is used by _FIT
+ method to read a piece of FIT data from QEMU.
_FIT method uses Read_FIT function to fetch NFIT structures blob from QEMU
in 1 page sized increments which are then concatenated and returned as _FIT method result.
okay.
+
+ Input parameters:
+ Arg0 – UUID {set to 648B9CF2-CDA1-4312-8AD9-49C4AF32BD62}
+ Arg1 – Revision ID (set to 1)
+ Arg2 - Function Index, 0x1
+ Arg3 - A package containing a buffer whose layout is as follows:
+
+ +----------+-------------+-------------+-----------------------------------+
+ | Filed | Byte Length | Byte Offset | Description |
^ field, s/Byte//, s/Byte//
+ +----------+-------------+-------------+-----------------------------------+
+ | offset | 4 | 0 | the offset of FIT buffer |
offset in QEMU's NFIT structures blob to read from
okay.
+ +----------+-------------+-------------+-----------------------------------+
+
+ Output:
+ +----------+-------------+-------------+-----------------------------------+
+ | Filed | Byte Length | Byte Offset | Description |
+ +----------+-------------+-------------+-----------------------------------+
+ | | | | return status codes |
+ | | | | 0x100 indicates fit has been |
+ | status | 4 | 0 | updated |
0x100 - error caused by NFIT update while read by _FIT wasn't completed
okay.
+ | | | | other follows Chapter 3 in DSM |
s/other follows/other codes follow/
okay.
+ | | | | Spec Rev1 |
+ +----------+-------------+-------------+-----------------------------------+
+ | fit data | Varies | 4 | FIT data |
+ | | | | |
+ +----------+-------------+-------------+-----------------------------------+
what does "Varies" mean, how would I know reading this how much data Read_FIT should read
from shared page?
I mean other bytes in the buffer returned by this function except the 'status' field
will be used as fit data. Maybe it is has a 'length' field?
+
+ The FIT offset is maintained by the caller itself,
probably is not necessary sentence, or specify a caller (for example OSPM)
Okay.
current offset plugs
^^^^?
Typo. should be plus.
+ the length returned by the function is the next offset we should read.
+ When all the FIT data has been read out, zero length is returned.
+
+ If it returns 0x100, OSPM should restart to read FIT (read from offset 0
+ again).
[...]
that's all for doc part, I'll do the code part later.
Thank you, Igor.
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