The last category of BlockIds to consider is the MUXWAIT. This has a BlockId of the form:
fffdssss where ssss is the slot id of the waiting thread.
A MUXWAIT is a multiplex semaphore wait. The semaphore comprising the MUX list may be:
RAMSEMs
SYSSEMs
32-bit Event & Mutex SEMs
We will consider each of these in turn.
The first step is to format the muxtable. This comprises 9-byte entries. +0x2 is the slot number of the waiter. +0x5 indicates the type of semaphore. +5 is the semaphore handle, which is interpreted according to type as follows:
0x00
The following shows an example formatted MUXTABLE. There are up to 255 entries, but in practise the entries in use are grouped at the beginning of the table.
# db muxtable+(9*0) l90400:000048be c7 48 14 00 02 1a 07 be-00 GH.....>.
# db muxtable+(9*1) l9
0400:000048c7 d0 48 15 00 02 5c 07 be-00 PH...\.>.
# db muxtable+(9*2) l9
0400:000048d0 ff ff 15 00 02 78 07 be-00 .....x.>.
# db muxtable+(9*3) l9
0400:000048d9 e2 48 1f 00 02 58 07 fa-03 bH...X.z.
# db muxtable+(9*4) l9
0400:000048e2 fd 48 1f 00 02 5c 07 fa-03 }H...\.z.
# db muxtable+(9*5) l9
0400:000048eb c3 49 1f 00 02 50 07 fa-03 CI...P.z.
# db muxtable+(9*6) l9
0400:000048f4 57 49 58 00 02 61 01 64-07 WIX..a.d.
# db muxtable+(9*7) l9
0400:000048fd 06 49 1f 00 02 60 07 fa-03 .I...`.z.
# db muxtable+(9*8) l9
0400:00004906 0f 49 1f 00 02 64 07 fa-03 .I...d.z.
# db muxtable+(9*9) l9
0400:0000490f 18 49 1f 00 02 68 07 fa-03 .I...h.z.
# db muxtable+(9*a) l9
0400:00004918 a8 49 1f 00 02 6c 07 fa-03 (I...l.z.
# db muxtable+(9*b) l9
0400:00004921 2a 49 58 00 01 f0 53 00-00 *IX..pS..
# db muxtable+(9*c) l9
0400:0000492a cc 49 30 00 03 02 a7 f1-00 LI0...'q.
# db muxtable+(9*d) l9
0400:00004933 3c 49 1b 00 01 9c 53 00-00 <I....S..
# db muxtable+(9*e) l9
0400:0000493c be 48 1b 00 03 da a6 f1-00 >H...Z&q.
# db muxtable+(9*f) l9
0400:00004945 4e 49 63 00 01 fc 53 00-00 NIc..|S..
# db muxtable+(9*10) l9
0400:0000494e eb 48 63 00 01 32 54 00-00 kHc..2T..
# db muxtable+(9*11) l9
0400:00004957 60 49 58 00 01 e4 53 00-00 `IX..dS..
# db muxtable+(9*12) l9
0400:00004960 ba 49 58 00 01 ea 53 00-00 :IX..jS..
# db muxtable+(9*13) l9
0400:00004969 72 49 57 00 01 ba 53 00-00 rIW..:S..
# db muxtable+(9*14) l9
0400:00004972 7b 49 57 00 01 c0 53 00-00 {IW..@S..
# db muxtable+(9*15) l9
0400:0000497b 84 49 57 00 01 c6 53 00-00 .IW..FS..
# db muxtable+(9*16) l9
0400:00004984 8d 49 57 00 01 cc 53 00-00 .IW..LS..
# db muxtable+(9*17) l9
0400:0000498d 96 49 57 00 01 d2 53 00-00 .IW..RS..
# db muxtable+(9*18) l9
0400:00004996 9f 49 57 00 01 d8 53 00-00 .IW..XS..
# db muxtable+(9*19) l9
0400:0000499f f4 48 57 00 01 de 53 00-00 tHW..^S..
# db muxtable+(9*1a) l9
0400:000049a8 b1 49 21 00 02 a8 07 fa-03 1I!..(.z.
# db muxtable+(9*1b) l9
0400:000049b1 33 49 21 00 03 ee a6 f1-00 3I!..n&q.
# db muxtable+(9*1c) l9
0400:000049ba 45 49 58 00 01 f0 53 00-00 EIX..pS..
# db muxtable+(9*1d) l9
0400:000049c3 d9 48 1f 00 02 54 07 fa-03 YH...T.z.
# db muxtable+(9*1e) l9
0400:000049cc d5 49 00 00 00 00 00 00-00 UI.......
# db muxtable+(9*1f) l9
0400:000049d5 de 49 00 00 00 00 00 00-00 ^I.......
# db muxtable+(9*20) l9
0400:000049de e7 49 00 00 00 00 00 00-00 gI.......
# db muxtable+(9*21) l9
0400:000049e7 f0 49 00 00 00 00 00 00-00 pI.......
# dp %%f1a6da l2
In this example there are only semaphore types 0, 1, 2 and 3. We will illustrate unravelling each of these in turn. For type 4 see the later section on 32-Bit Semaphores.