09107: pcipc(s7): Bios cannot recognize the hard disk size correctly.

ID	Category [?]	Severity [?]	Reproducibility	Date Submitted	Last Update
09107	Media Support	Major	Always	Feb 8, 2025, 04:12	21 days ago

Tester	VasiliyFamiliya	View Status	Public	Platform	MAME (Official Binary)
Assigned To		Resolution	Invalid report	OS	Windows 10/11 (64-bit)
Status [?]	Closed			Driver	pc/pcipc.cpp
Version	0.274	Fixed in Version		Build	64-bit
		Fixed in Git Commit		Github Pull Request #

Summary	09107: pcipc(s7): Bios cannot recognize the hard disk size correctly.
Description	As a result, we have a stuck at the middle of formatting before OS install.
Steps To Reproduce	Select an attached blank CHD as a hard disk image (its actual logical size is 5120 MB) and go to BIOS settings menu.
Additional Information	sis85c496 machine from pcipc_sis driver also has this bug (see the screenshots).
Github Commit

Flags
Regression Version
Affected Sets / Systems	pcipc(s7)

Attached Files	pcipc.png (12,648 bytes) Feb 8, 2025, 04:12 Uploaded by VasiliyFamiliya
	pcipcs7.png (12,572 bytes) Feb 8, 2025, 04:13 Uploaded by VasiliyFamiliya
	sis85c496.png (19,591 bytes) Feb 8, 2025, 04:13 Uploaded by VasiliyFamiliya
	MyWin.zip (5,605 bytes) Feb 8, 2025, 04:14 Uploaded by VasiliyFamiliya

No.22970 Robbbert Moderator Feb 8, 2025, 04:48 edited on: Feb 8, 2025, 04:48	A lot of older bioses had limits on what size hard drive they could properly support. For example, a 386 computer would not normally handle more than 512MB. DOS itself is limited to 2GB maximum. Using a 5.4 GB drive? No idea what support you could expect.
No.22971 VasiliyFamiliya Tester Feb 8, 2025, 05:19	As I noted earlier, the real HD size is 5.0 GB. For some reason, BIOS "sees" a 249 MB more than HD really have.
No.23027 cuavas Administrator 21 days ago edited on: 19 days ago	What C/H/S parameters did you use to create the disk? The numbers it’s showing are correct for the suggested C/H/S mappings: * 512×652×25563 = 5,362,882,560 bytes, rounded to 5,363 million bytes 512×16,384×16×40 = 5,368,709,120 bytes, rounded to 5,369 million bytes * 512×8,192×32×40 = 5,368,709,120 bytes, rounded to 5,369 million bytes 5 GiB = 5×1024×1024*1024 = 5,368,709,120 bytes. It’s seeing the correct size, and giving three suggested mappings that give no more than the actual size. You’re confusing the displayed value in megabytes (MB, 10^6) for mebibytes (MiB, 2^20). If you can’t give actual evidence that it isn’t detecting the disk correctly, this should be closed.
No.23033 cuavas Administrator 21 days ago	The premise of the report, that the BIOS is choosing an incorrect size when detecting the disk and choosing geometry, is incorrect and based on a bad assumption.