Yes, I can confirm that. The Pi Zero is running a 32-bit OS on top of a 32-bit kernel. János Greg KH <greg@xxxxxxxxx> ezt írta (időpont: 2020. júl. 21., K, 16:23): > > On Tue, Jul 21, 2020 at 02:20:27PM +0200, SZIGETVÁRI János wrote: > > Hi Alan, > > > > Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> ezt írta (időpont: 2020. júl. > > 20., H, 19:29): > > > 4.19 is a very old kernel. You'd be a lot better off testing under a > > > recent kernel, like 5.7. It also would be more convenient to do your > > > development on a regular PC instead of a Raspberry Pi. You can use > > > dummy-hcd for testing gadget drivers. > > > > Okay, I put together a Slackware-current based VM to conduct the > > development work on. > > I compiled a patched version of kernel 5.7.9 with all the necessary > > config parameters to have USB gadget support with debugging enabled, > > and also the dummy HCD. > > > > At first loaded the g_mass_storage module with a smaller ~700 MB iso > > file, and it loaded seemingly fine, and functionality-wise it also > > seemed to work fine, although there were frequent periodical debug > > messages about the gadget returning command-failure status: > > https://gist.github.com/jszigetvari/5bc4cdc8c55588907b71832558cb00a7 > > > > After that as a test I tried to dd all the data from /dev/sr1 (that's > > the device file the gadget was assigned) to /dev/null. > > The process completed without any user-visible errors, although the > > failure status related messages kept on appearing: > > https://gist.github.com/jszigetvari/ffa19850c94f12510c0b78ed5aaba2e1 > > > > Finally I tried to load the large, 11 GB CentOS iso file as the second > > phase of the test. On the Raspberry Pi (with kernel 4.19) this was > > when the crash happened, however this time it did not. > > Originally Tiziano Bacocco's patch came around to be the time of the > > 3.x kernels. The patch needed minimal adjustments to apply to 4.19 and > > 5.4 and also to 5.7.9 (though there was a one line offset in > > f_mass_storage.c). > > https://gist.github.com/jszigetvari/5a9796c8af8a01c0edba6a8696540029 > > > > Although I have to admit that on the Pi Zero I was using the g_multi > > kernel module, and not g_mass_storage I assumed they share the same > > code base, so they should work the same way. > > On the Pi zero I need the extra serial and Ethernet interface to have > > access to the Pi Zero, as it doesn't have a wireless NIC, and that's > > why I chose g_multi.ko. > > > > In the end I did a dd with the 11 GB iso, and to my surprise it worked > > well. dd returned without any errors and it did show the true 11 GB > > size when it finished. > > In the kernel logs most log entries were about block reads, but the > > failure status messages were still around. If there was no activity on > > the device, then they accounted for the majority of the logs > > generated: > > https://gist.github.com/jszigetvari/a9225fa3173e6c7b7b50673a494d9c37 > > > > I have to admit, I stand puzzled why it worked on an x86_64-based > > machine and crashed on the Pi Zero. > > I guess the next step will be either: > > * to try using g_multi instead of g_mass_storage on the test machine > > * upgrade the Pi Zero to run kernel 5.4.x (AFAIK that's the latest one > > can get from the Raspberry Pi Foundation's git repo), and recompile > > that kernel version with the patch applied. (This will likely take a > > few days.) > > > > Any further suggestions would also be welcome! > > One guess, the Pi Zero is running a 32bit kernel, while your desktop is > running a 64bit one? > > greg k-h
