MEGA65: All .d81 being accessed on the virtual SD card image are R/O

[nobruinfo]

Describe the bug

Used version of the project

• Emulator: Xemu65
• Version: November 9, 2023
• ROM: 920385
• CLI arguments: none
• Context menu options: Debug system console
• .img used: newly generated by "SD-Card", "Update files on SD-Card"

To Reproduce

If CLI switch -defd81fromsd isn't used the issue does not appear when mounting mega65.d81 or external.d81. Those are then written/read in the HDOS folder even though -hdosvirt isn't used. Altogether this seems indicating the issue only affects files being accessed within the SD card where probably other files are not written back to.

The versions 20230201 and before did not have this issue. There might be more versions but I only downloaded the later 20230513 with which I first see the behaviour.

To replicate the switch -hdosvirt must not be set. Thanks for fixing.

Expected behavior

All .d81 (no matter if HDOS, default or by -defd81fromsd) should allow writing back into .d81 files.

Screenshots

Computer/Device (please complete the following information)

• Device/Platform: PC
• OS and its version: Windows 10 22H2 64bit
• Browser and its version - if applies: N/A

Additional context

None.

[lgblgblgb]

NOTE (for myself): Part of #367 in some way, but a very specific issue, so keep it separated but related.

[lgblgblgb]

After issuing MOUNT "SOMETHING.D81" in BASIC65, on the stdout ("sysconsole") of the emulator:

SDCARD: MOUNT: internal mount #0 from SD sector $3320 (R/O)
D81: previous file descriptor (34) is NOT closed, because marked as non-autoclose!
D81: fd 34 has been attached to #0 with 6701056 offset, read_only = 1, autoclose = 0, size = 819200
SDCARD: configuring F011 FDC (#0) with have_disk=1, can_write=0, image_size=819200, d81_access="D81 (M:0,A=$00,B=$07)
HDOS: leaving function #$40 (d81attach0) with carry SET (A,X,Y,Z=$40,$08,$0D,$00)
HDOS: d81attach0("external.d81") = OK

So it's clear that the SDCARD/D81 subsystem is literally asked to do R/O mount (read_only = 1 and can_write = 0). Surely, it's more than likely that the source which asks this is also at Xemu's side, that's true ... But this tighten the problem down a bit, as it's not the mounting itself which does something wrong, it already gets the request this way, to be R/O.

[nobruinfo]

@lgblgblgb Oh, I completely mistook the discussion over at Discord then. I thought the sd_regs[ ] being read from what comes from either the device or the media.

I now could reproduce the exact lines you show. Understood.

[lgblgblgb]

The commit above (already in the newest next release) tries to work around this problem by forcing R/W mount even if HDOS wants to do R/O only. I am not sure if it has any ill side effects, it seems to work for me.

[nobruinfo]

@lgblgblgb Thank you very much. Sound like the dirtiest workaround, so why not? ;) I'm quite busy right now but will definitely test it and give feedback.