libmdbx on gramine

[tiagorvmartins]

Hey Gramine team, would appreciate some assistance,
Been trying to run an application that depends on libmdbx, already enabled experimental flock but still having issues.

The error seems to be:
mdbx_env_open: function not implemented

Which I believe is trying to do some kind of file locking unsupported on Gramine?

Some supporting info here:
mdbx_env_open

Below, a few debug log lines when running on gramine:

[INFO] [11-21|20:16:48.095] Set global gas cap                       cap=50000000
[INFO] [11-21|20:16:48.098] [Downloader] Running with                ipv6-enabled=true ipv4-enabled=true download.rate=16mb upload.rate=4mb
[INFO] [11-21|20:16:48.099] Opening Database                         label=data path=/tmp/data
PATH:  /tmp/data
FLAGS:  41943040
(libos_stat.c:185:__do_statfs) [P1:T1:app] debug: statfs: 20000000 10000000 10000000
(libos_stat.c:185:__do_statfs) [P1:T1:app] debug: statfs: 20000000 10000000 10000000
mdbx_env_open: function not implemented
(libos_context.c:279:prepare_sigframe) [P1:T1:app] debug: Created sigframe for sig: 23 at 0xc00000f390 (handler: 0x4947c0, restorer: 0xa5e97ef2e0)
[EROR] [11-21|20:16:48.136] App startup                           err="mdbx_env_open: function not implemented, label: data, trace: [kv_mdbx.go:361 node.go:367 node.go:370 backend.go:270 node.go:131 main.go:73 make_app.go:46 command.go:276 app.go:333 app.go:307 main.go:46 proc.go:267 asm_amd64.s:1650]"
mdbx_env_open: function not implemented, label: data, trace: [kv_mdbx.go:361 node.go:367 node.go:370 backend.go:270 node.go:131 main.go:73 make_app.go:46 command.go:276 app.go:333 app.go:307 main.go:46 proc.go:267 asm_amd64.s:1650]
(libos_exit.c:205:libos_syscall_exit_group) [P1:T1:app] debug: ---- exit_group (returning 1)
(libos_async.c:109:install_async_event) [P1:T2:app] debug: Installed async event at 1732220208137588
(libos_async.c:109:install_async_event) [P1:T8:app] debug: Installed async event at 1732220208137588
(libos_async.c:109:install_async_event) [P1:T7:app] debug: Installed async event at 1732220208137607

Any clues what can be done?
Thank you!

[kailun-qin]

@tiagorvmartins: Can you pls provide the "trace" Gramine logs? Thanks!

[tiagorvmartins]

Hey @kailun-qin I happen to use another build flags and eventually was able to use another locking system,
But now I am facing another issue, which was unexpected,
Question: isn't pwritev supported in gramine?
Looked at the docs and I believe it is, but wanted to double check.

Getting on trace logs:
warning: Unsupported system call pwritev

Thank you!

[kailun-qin]

Question: isn't pwritev supported in gramine?

No, it's currently unsupported:

gramine/libos/src/arch/x86_64/libos_table.c

Line 313 in 5789620

[__NR_pwritev] = (libos_syscall_t)0, // libos_syscall_pwritev

[tiagorvmartins]

Okay I see now that explains it, but docs are outdated then I guess?
I see this in the docs:

☑ pwritev() 9a

Thank you!

[kailun-qin]

Okay I see now that explains it, but docs are outdated then I guess?

Yeah, I noticed that discrepancy in the doc -- it's not correct.

[tiagorvmartins]

Okay thank you, I managed to work around it using a wrapper around pwritev leveraging pwrite64.
For now seems to have solved the problem, thank you again @kailun-qin !