Weird FontInstall fail

Trying a *FontInstall (with no parameters) caused a crash in CLib (which means something else crashed and CLib was left with its balls in its hands).

I’m using RISC OS 5.29 dated 23rd April 2023.

Command line transcript:

*FontInstall
Internal error: abort on data transfer at &FC195954
*FX 0
RISC OS 5.29 (23 Apr 2023)
*Where
Address &FC19595C is at offset &00013838 in module 'SharedCLibrary'
*MemoryI PC-20 +40
FC19593C : ôÿÿ. : 0AFFFFF4 : BEQ     &FC195914
FC195940 : . .à : E0022000 : AND     a3,a3,a1
FC195944 : ...à : E0031000 : AND     a2,a4,a1
FC195948 : ..Bà : E0420001 : SUB     a1,a3,a2
FC19594C : .ŵ½è : E8BD8200 : LDMIA   sp!,{sb,pc}
FC195950 : . Ðä : E4D02001 : LDRB    a3,[a1],#1
FC195954 : .0Ñä : E4D13001 : LDRB    a4,[a2],#1
FC195958 : .0Rà : E0523003 : SUBS    a4,a3,a4
FC19595C < .... : 1A000001 : BNE     &FC195968
FC195960 : ..Rã : E3520000 : CMP     a3,#0
FC195964 : ùÿÿ. : 1AFFFFF9 : BNE     &FC195950
FC195968 : .. á : E1A00003 : MOV     a1,a4
FC19596C : .ŵ½è : E8BD8200 : LDMIA   sp!,{sb,pc}
FC195970 : @@-é : E92D4040 : STMDB   sp!,{v3,lr}
FC195974 : .0ۇ : E1803001 : ORR     a4,a1,a2
FC195978 : ...ã : E3130003 : TST     a4,#3
*ShowRegs
Register dump (stored at &20003110) is:
R0  = 42E7C051 R1  = 42E860ED R2  = 0000005F R3  = 00000096
R4  = 00000000 R5  = 42E7BB9C R6  = 42E860ED R7  = 42E67DAC
R8  = 201103D0 R9  = 00040091 R10 = FA20021C R11 = FA207E7C
R12 = FA207E80 R13 = FA207E5C R14 = FC492540 R15 = FC19595C
Mode SVC32 flags set: nzCvqjggggeAift        PSR = 20000113
*

And to shed some light on what’s going on here, from the exception dump…

SVC stack:
fa207e5c : 00040091 : - R9
fa207e60 : fc492540 : | R14: fc492540 (ASM call to fc1958d4)
         :          : | fc492540 = FontDbox +484
         :          : | fc1958d4 = SharedCLibrary +137b0
fa207e64 : 42e5d43c : - R4
fa207e68 : 42e67dac : | R5
fa207e6c : 201103cc : | R6
fa207e70 : fa207e9c : | R11
fa207e74 : fa207e80 : | R12
fa207e78 : fc494990 : | R14: fc494990
         :          : | = FontDbox +28d4
fa207e7c : fc492518 : | APCS function: fc492510
         :          : | = FontDbox +454
fa207e80 : 00000096 : | R4
fa207e84 : 00000000 : | R5
fa207e88 : 00000000 : | R6
fa207e8c : 42e7c9ff : | R7
fa207e90 : fa207eec : | R11
fa207e94 : fa207ea0 : | R12                                      - R4
fa207e98 : fc4924d8 : | R14: fc4924d8                            | R5
         :          : | = FontDbox +41c                          | 
fa207e9c : fc49494c : | APCS function: fc494944                  | R6
         :          : | = FontDbox +2888                         | 
fa207ea0 : 00000301 : |                                          | R7
fa207ea4 : 42e7c9ff : |                                          | R8
fa207ea8 : ffffffff : |                                          | R9
fa207eac : 00000000 : |                                          | R11
fa207eb0 : fa207ebc : |                                          | R12
fa207eb4 : fc2187a4 : |                                          | R14: fc2187a4
         :          : |                                          | = DWCDriver +2d6c
fa207eb8 : fc221f98 : |                                          | APCS function: fc221f90
         :          : |                                          | = DWCDriver +c558
fa207ebc : 23f59ec8 : | 
fa207ec0 : 2000bba8 : | 
fa207ec4 : fa207ef4 : | 
fa207ec8 : 23f59ec8 : | R4
fa207ecc : 23c7a950 : | R5
fa207ed0 : 40000113 : | R6
fa207ed4 : fc017ed8 : | R7                                       - Return to fc017ed8?
         :          : |                                          | = +17ed8 in the Kernel
fa207ed8 : 00000001 : | R8
fa207edc : fc492198 : | R9
fa207ee0 : fa207efc : | R11
fa207ee4 : fa207ef0 : | R12
fa207ee8 : fc494250 : | R14: fc494250
         :          : | = FontDbox +2194
fa207eec : fc492398 : | APCS function: fc492390
         :          : | = FontDbox +2d4
fa207ef0 : 00000000 : | R11
fa207ef4 : fa207f00 : | R12
fa207ef8 : fc4921f0 : | R14: fc4921f0
         :          : | = FontDbox +134
fa207efc : fc4941ec : | APCS function: fc4941e4
         :          : | = FontDbox +2128
fa207f00 : 2004c244 :
fa207f04 : 0000006e :
fa207f08 : 2042d414 :
fa207f0c : 2042d414 :
fa207f10 : 00000003 :
fa207f14 : 000025e0 :
fa207f18 : 00000001 :
fa207f1c : 000000bc :
fa207f20 : 00000001 :
fa207f24 : fc492198 :
fa207f28 : 0000006e :
fa207f2c : 30110db8 :
fa207f30 : fc017ed8 : - Return to fc017ed8?
         :          : | = +17ed8 in the Kernel
fa207f34 : 30110dc4 :
fa207f38 : 00000001 : - R9
fa207f3c : 00000013 : | R10
fa207f40 : 00000030 : | R11
fa207f44 : 20000113 : | R12
fa207f48 : fc0108e8 : | R14: fc0108e8 (ASM call to fc017e60)
         :          : | fc0108e8 = +108e8 in the Kernel
         :          : | fc017e60 = +17e60 in the Kernel
fa207f4c : 20000113 : - PSR?
fa207f50 : 00020030 : | SWI XOS_ServiceCall
fa207f54 : fc271c14 : | R14: fc271c14
         :          : | = FontManager +2fec
fa207f58 : 00000001 : | R10
fa207f5c : 30002d44 : | R11
fa207f60 : 2004b854 : | R12
fa207f64 : 00000000 :
fa207f68 : 60000113 :
fa207f6c : 00000000 : - R1
fa207f70 : fc26edac : | R2
fa207f74 : fc26ec28 : | R3
fa207f78 : 00000000 : | R4
fa207f7c : fc271220 : | R14: fc271220 (ASM call to fc271b84)
         :          : | fc271220 = FontManager +25f8
         :          : | fc271b84 = FontManager +2f5c
fa207f80 : fa454800 :
fa207f84 : 00000000 :
fa207f88 : 30002d5c :
fa207f8c : fc0139a0 : - Return to fc0139a0?
         :          : | = +139a0 in the Kernel
fa207f90 : 000000bc :
fa207f94 : fc26eda0 :
fa207f98 : 205be8b4 : - R0
fa207f9c : 00000060 : | R2
fa207fa0 : 3010dc68 : | R3
fa207fa4 : 00000001 : | R4
fa207fa8 : 00000000 : | R5
fa207fac : 2005bd94 : | R6
fa207fb0 : 205b0f94 : | R7
fa207fb4 : 00000001 : | R8
fa207fb8 : 00000000 : | R9
fa207fbc : 00000046 : | R10
fa207fc0 : fc01353c : | R14: fc01353c (ASM call to fc013798)
         :          : | fc01353c = +1353c in the Kernel
         :          : | fc013798 = +13798 in the Kernel
fa207fc4 : 000000ff : [etc etc]

At a cursory look, FontManager “does stuff” then issues a Service Call and then… wait, what? The font selector box in the USB driver chokes? Surely that’s not right? Why is the USB driver doing anything Wimpy? And why the hell does it have FontDBox?!?

FontDBox 0.19 2023/01/25
DWCDriver 0.37 2020/07/04
SharedCLibrary 6.19 2023/02/22
FontManager 3.80 2020/07/20

Bonjour Rick
I updated SharedCLibrary about a month ago to version 6.20 and the star FontInstall command does not throw an error.
No DWCDriver loaded.
FontDbox and FontManager are same.

So, come back today and it’s working.

So we can discount the generic OS ROM bits, WindowScroll, Pinboard2, MiniTime, ChooseBD (mine), Amu, Zap, StrongHelp, and NetSurf as well as AcornURI.

Running R-Comp network stack, with LanManFS, Freeway/ShareFS, RemotePrinterFS, and all the crap that gets loaded by Amu, Zap, and NetSurf.

*Show Font*
Font$Path(Macro) : NetSurf:Resources.Fonts.,SDFS::RISCOSPi.$.!BOOT.Resources.!Fonts.,<Font$Prefix>.,Resources:$.Fonts.
Font$Prefix :  
FontDbox$Path : Resources:$.Resources.FontDbox.
FontMenu$Path : Resources:$.Resources.FontMenu.
FontPrint$Dir : SDFS::RISCOSPi.$.Printing.!FontPrint
*

All looks pretty normal.

So I guess, when I remember, I’ll have to keep doing FontInstall commands to see when/if it fails and try to remember what I did.

<scratches head> These sorts of bugs annoy me. Luckily I have just made tea so that’ll make me feel better. :)

Edit: Add DrawPlus to the good list.

How strange that it’s now working for you! I might be miles out here, but isn’t/wasn’t there some hackery between the USB stack and the Wimp to get the scroll wheel working? Maybe that’s been removed here days?

Ah… this is what I was thinking of. Jeffrey binned it a long while ago: https://gitlab.riscosopen.org/RiscOS/Sources/HWSupport/USB/USBDriver/-/commit/8d06c374cd606f0ecc70b794530e884201e5a0df

Update the SharedCLibrary to version 6.20 which might resolve the crash related to FontInstall and investigate any potential conflicts or unexpected interactions between FontDBox, FontManager and the USB driver to rectify unexpected behavior.