5 ms·

Unless they fixed it, another edge case is a change in processor endianness. I started working on a patch a long time ago, but it necessitated changes to code t

Unless they fixed it, another edge case is a change in processor endianness. I started working on a patch a long time ago, but it necessitated changes to code that had remained unchanged since the original release... not a blamelog I'm totally comfortable with.

Filligree 5y ago
I hadn’t heard of that one. Does send |receive still work?
- sennight 5y ago
  Nope, the system would instantly panic - presumably in order to protect data integrity... imagine the damage possible otherwise. It was actually a fairly ponderous debugging effort, as I remember it, because it was occurring on an already shaky POWER9 setup I was using to port other stuff. ZFS worked great for any vdev setup on any OS compiled with the same endianness, but plugging in so much as a thumb drive previously provisioned from a different endian host... insta-console-vomit. Definitely an uncommon problem though :)
rincebrain 5y ago
What? CPU endianness switches work fine, IME - I have pools I originated on SPARC Solaris that work fine on x86, I just got a patch landed for an edge case in one recent feature not interoperating properly between endiannesses but other than that it's worked fine for me. What kind of issue did you see?
- sennight 5y ago
  > CPU endianness switches work fine Thats great news, hopefully that rare potential problem got addressed in the last year or so. Steps to recreate: compile linux (maybe FreeBSD as well, that is a little more fuzzy) for LE. Boot new kernel and setup a new pool. Recompile for BE. Boot new kernel and enjoy bootloop... lol, actually things are starting to come more into focus... page size played a role in the whole thing. As I said, edge case :) No potential for data loss though.
  - rincebrain 5y ago
    I'm guessing this was probably PPC, given the rarity of the other options? Sounds like a fun experiment to run down. Maybe I'll go look when I'm done the current nightmare I'm tinkering with.
    - sennight 5y ago
      Yup, Raptor Blackbird. I'd send along my notes if I didn't think they'd be more misleading than helpful. Left that one in a mess that'd be difficult to untangle, but I remember the trail basically ending in a file that was practically unchanged since the original source got released. Because of the code vintage I really wanted to be sure that I didn't introduce performance regressions, so that led to me turning my attention to live kernel debugging over serial, which led to uncovering an even more ancient tty bug (seriously, we're talking unix fountainhead old). She swallowed the spider to catch the fly... I'm presently writing something to crack 8051 firmware xnor'd by a 64 byte key, I don't remember how - but the previously described ZFS edge case somehow got me to this point.
      - rincebrain 5y ago
        I am...familiar with falling down rabbit holes. I cut a patch to fix sparc64 building with the new zstd feature. I then discovered the new zstd feature was broken for endian portability because lol bitfields.

Filligree 5y ago

I hadn’t heard of that one. Does send |receive still work?

sennight 5y ago
Nope, the system would instantly panic - presumably in order to protect data integrity... imagine the damage possible otherwise. It was actually a fairly ponderous debugging effort, as I remember it, because it was occurring on an already shaky POWER9 setup I was using to port other stuff. ZFS worked great for any vdev setup on any OS compiled with the same endianness, but plugging in so much as a thumb drive previously provisioned from a different endian host... insta-console-vomit. Definitely an uncommon problem though :)

rincebrain 5y ago

What? CPU endianness switches work fine, IME - I have pools I originated on SPARC Solaris that work fine on x86, I just got a patch landed for an edge case in one recent feature not interoperating properly between endiannesses but other than that it's worked fine for me. What kind of issue did you see?

sennight 5y ago
> CPU endianness switches work fine Thats great news, hopefully that rare potential problem got addressed in the last year or so. Steps to recreate: compile linux (maybe FreeBSD as well, that is a little more fuzzy) for LE. Boot new kernel and setup a new pool. Recompile for BE. Boot new kernel and enjoy bootloop... lol, actually things are starting to come more into focus... page size played a role in the whole thing. As I said, edge case :) No potential for data loss though.
- rincebrain 5y ago
  I'm guessing this was probably PPC, given the rarity of the other options? Sounds like a fun experiment to run down. Maybe I'll go look when I'm done the current nightmare I'm tinkering with.
  - sennight 5y ago
    Yup, Raptor Blackbird. I'd send along my notes if I didn't think they'd be more misleading than helpful. Left that one in a mess that'd be difficult to untangle, but I remember the trail basically ending in a file that was practically unchanged since the original source got released. Because of the code vintage I really wanted to be sure that I didn't introduce performance regressions, so that led to me turning my attention to live kernel debugging over serial, which led to uncovering an even more ancient tty bug (seriously, we're talking unix fountainhead old). She swallowed the spider to catch the fly... I'm presently writing something to crack 8051 firmware xnor'd by a 64 byte key, I don't remember how - but the previously described ZFS edge case somehow got me to this point.
    - rincebrain 5y ago
      I am...familiar with falling down rabbit holes. I cut a patch to fix sparc64 building with the new zstd feature. I then discovered the new zstd feature was broken for endian portability because lol bitfields.