4 ms·

This actually bit me earlier this week when I had to write a Windows 11 iso to a usb stick. Using dd on macos, everything seemed like it wrote ok. Checksums mat

This actually bit me earlier this week when I had to write a Windows 11 iso to a usb stick. Using dd on macos, everything seemed like it wrote ok. Checksums matched. All of that. Yet when I booted the target machine with the usb stick, windows installer kept asking for drivers. Back and forth with the motherboard manufacturer and debugging and I narrowed it down to this bug in dd which skipped a few bits (or wrote them incorrectly). Needless to say, I used a friends windows machine to make an install stick using Microsoft’s media creation tool and that worked out of the box. Strange. The only other explanation I have is that their direct download iso was corrupt or that this dd bug prevented it from writing correctly. UDF file format. Bootable image. UEFI. SecureBoot enabled. Standard Intel chipset.

withinboredom 4y ago
Almost identical problem earlier last month, except it made the drive read-only and had to fix it from Linux. Both Windows and OSX couldn’t fix it.
pronoiac 4y ago
> The only other explanation I have is that their direct download iso was corrupt I definitely got this impression, after a 2 or 4 gig boundary was crossed. I think I tried a Raspberry Pi to rule out a Mac issue. I had success with https://github.com/WoeUSB/WoeUSB-ng https://github.com/WoeUSB/WoeUSB-ng .
- stazz1 4y ago
  what does a checksum do
  - pronoiac 4y ago
    Sorry, I didn't mean "the iso was mangled in transit," I meant "they appear to not understand iso." The iso checksum verified without issue. Looking into it a bit, this might have something to do with UEFI firmware that only had FAT32 drivers. It started the install fine, but it broke when it hit a 4+ gig file, which would probably look truncated.
    - stazz1 4y ago
      i'm curious if bits can be altered and the checksum is the same -- it seems like checksum is for file length but not necessarily contents?
culpable_pickle 4y ago
> and I narrowed it down to this bug in dd which skipped a few bits (or wrote them incorrectly) Which bug in dd?

withinboredom 4y ago

Almost identical problem earlier last month, except it made the drive read-only and had to fix it from Linux. Both Windows and OSX couldn’t fix it.

pronoiac 4y ago

> The only other explanation I have is that their direct download iso was corrupt I definitely got this impression, after a 2 or 4 gig boundary was crossed. I think I tried a Raspberry Pi to rule out a Mac issue. I had success with https://github.com/WoeUSB/WoeUSB-ng https://github.com/WoeUSB/WoeUSB-ng .

stazz1 4y ago
what does a checksum do
- pronoiac 4y ago
  Sorry, I didn't mean "the iso was mangled in transit," I meant "they appear to not understand iso." The iso checksum verified without issue. Looking into it a bit, this might have something to do with UEFI firmware that only had FAT32 drivers. It started the install fine, but it broke when it hit a 4+ gig file, which would probably look truncated.
  - stazz1 4y ago
    i'm curious if bits can be altered and the checksum is the same -- it seems like checksum is for file length but not necessarily contents?

culpable_pickle 4y ago

> and I narrowed it down to this bug in dd which skipped a few bits (or wrote them incorrectly) Which bug in dd?