An Easy2Boot user reported that he could not boot to a FAT12 partition image from his EeePC but it worked OK on QEMU and some other systems (TBC).
This pointed to a BIOS issue.
The partition image contained grub4dos.
We eventually found that whether it hung with a flashing cursor or it booted to grub4dos depended on the start position of the FAT12 partition on the USB drive. Here are some experimental results when booting on an EeePC.
This was reproduced on my EeePC as well as his.
On failure, the Flash drive's LED does flash a few times before it hangs with a flashing cursor so some sort of sector loading is occurring before the hang.
P1 Start=4,626,360 (2,368,696,320 bytes) End=4,627,959 (2,369,515,008 bytes)
P1 Start=4,623,160 (2,367,057,920 bytes) End=4,624,759 (2,367,876,608 bytes)
P1 Start=3,922,008 (2,008,068,096 bytes) End=3,923,607 (2,008,886,784 bytes)
WORKS !!!!!! boots to grub4dos
In all cases the contents of Ptn1 were byte-for-byte identical as a partition image was used only the start location was changed by changing the Primary partition table values (and the no. hidden sectors for partition offset in the BPB). e.g.
Partition 1 SIZE=0.781MiB Type: 0E FAT16LBA *ACTIVE*
START POS = CYL:1023 HD:254 SEC:63 END POS = CYL:1023 HD:254 SEC:63
START (LBA) = 3,922,008 (003BD858) SIZE (LBA) = 1,600 (00000640) [End=3,923,607]
Since it boots OK on other systems and QEMU and VBox, it must be some sort of EeePC bug (and probably other BIOSes too).
Any ideas? Looks like some sort of 2GB limit??
However, a FAT32 partition boots OK even if it starts way past 4GB on the drive - so it only seems to be a problem with the FAT12 partition.
Edited by steve6375, 25 September 2019 - 07:19 AM.