147
Linus Torvalds Lashes Out At RISC-V Big Endian Plans
(www.phoronix.com)
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
this post was submitted on 01 Oct 2025
147 points (100.0% liked)
Linux
9642 readers
390 users here now
A community for everything relating to the GNU/Linux operating system (except the memes!)
Also, check out:
Original icon base courtesy of lewing@isc.tamu.edu and The GIMP
founded 2 years ago
MODERATORS
Big endian is a byte order scheme. For registers and memory. If I'm not mistaken, pretty much all modern systems these days are little endian. The differences can largely be mitigated at the operating system level. But it definitely invites new chaos back into the equation. If programs don't get their bytes in the right order, it will be garbage in garbage out everywhere. Try playing an old PCM wave file from a 68k based Macintosh or Amiga on a PC.
Interesting, thank you for explaining what it is!
I really appreciate how specific this is. It sounds like it’s from experience.
It 100% is. I have distinct memories back in the 80s of getting a hold of files off of FidoNet, etc. and trying to play them only to find out they were big endian files. It sounded like a mildly uncomfortable shoggoth in a blender. It had nothing on the dulcet tones of dial up modems.
@Eldritch
I don‘t think the order of the bits and bytes in some file format depends on the byte order inside cpu registers.
If you have a file containing 4 bytes, where the first byte in the file is
0x01, second is0x02, third is0x03, and 4th is0x04, and you keep that same order when you load them into the first 4 bytes of memory on an LE machine vs a BE machine, what value does the uint32 located at address 0 contain? On LE it's0x04030201, on BE it's0x01020304. So yes, it absolutely matters.Not on RISC-V. The registers don't really have an endianness. They're just bit vectors - you can't address within them.
When you access memory the current endianness setting determines the mapping between the register value and the bytes in memory. It's the access that has endianness; not the register.
Some formats are designed around a particular endian-ness. But not all. Some only specify where a byte is to be stored and what it should represent. But not how it should be stored. PCM WAV files are ancient and uncompressed. with a few bytes in the headder telling you bit depth and sample rate. Followed by a stream of raw bytes representing the samples. Whether you store those bytes in LSB or MSB order. They're both valid. But passing such a file to a system expecting the opposite. Your file will still play. It will just be squealing noise.
Bitmap images can be similar as well. So arbitrary is the data in RAW Bitmap files. That you can open it in audio software like Audacity as a raw PCM. Perform Fourier transforms or other audio options on it. Save the raw byte stream back out as an image again. Bytes are bytes, and a lot of formats don't care what order they're in. Even if the user might.