IPC: Difference between revisions

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 IPC commands are written to the [[Thread Local Storage]] at offset 0x80 and submitted using [[SVC|svcSendSyncRequest]]. If the kernel was able to dispatch the request, the server reply will be written to TLS+0x80. Often the second word of the response data is the error code (or 0 if success).
-Every IPC command sent to services starts with a u32 header code, and parameters, if any, are written after this header. They are decomposed into the following parts:
+Every IPC command sent to IPC server processes starts with a u32 header code. Parameters, if any, are written following this header. There are "normal parameters", which are fixed-size words, and there are "translate parameters", which are of flexible size and each of which begins with a header. The entire command has the following structure:
+{| class="wikitable" border="1"
+|-
+!  Word
+!  Size
+!  Description
+|-
+| 0
+| 1
+| Header code
+|-
+| 1
+| x
+| Normal parameters
+|-
+| x
+| y
+| Translate parameters
+|}
+The IPC command header has the following structure:
 {| class="wikitable" border="1"
 |-
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 |-
 | 0-5
-| Number of translate parameters (=y)
+| Total size in words of the translate parameters (=y). Note that this is in general different from the number of translate parameters
 |-
 | 6-11
@@ Line 20: / Line 40: @@
 |}
-The entire command has the following structure:
+Each translate parameter starts with a translation descriptor:
 {| class="wikitable" border="1"
 |-
-!  Word
+!  Bits
-!  Size
 !  Description
 |-
-| 0
+| 1-3
-| 1
+| type
-| Header code
-|-
-| 1
-| x
-| Normal parameters
-|-
-| x
-| y
-| Translate parameters
 |}