WebUSBWebGPUWebPCIEWebNVMEWebSATAWebATX12V

@manawyrm @volpeon tell me more. I crave more.

@littlefox @volpeon
*sigh*
OK, you wanted it:

AMI MegaRAC (the BMC web UI for servers) has this feature where they allow you to select a .iso image for a CD-ROM in the web console (next to the KVM/VNC viewer).

How did they implement the CD-ROM emulation?
They open a WebSockets connection to the BMC, emulate a SCSI CD-ROM drive in JavaScript (!) and send raw SCSI packets back&forth via WebSockets, which the BMC then forwards via internal USB to the host system.

@littlefox @manawyrm @volpeon You really don't.

@elfin @manawyrm @volpeon I need all the knowledge

WebUSB
WebGPU
WebPCIE
WebNVME
WebSATA
WebATX12V

@littlefox @manawyrm @volpeon Some things just aren't healthy.

@elfin @manawyrm @volpeon I know
I never claimed this was healthy

@littlefox @manawyrm @volpeon Fair enough.

I've worked on some storage in my day and I have seen some shady shit ... but that kludge is horrific.

@elfin @littlefox @volpeon Littlefox knows me long enough to know that when I say: „oh god“, things are really bad 🤭

@manawyrm @elfin @volpeon

@volpeon WebSCSI!
(actually exists, curtesy of American Megatrends)

@manawyrm @littlefox @volpeon fun fact, the iDRAC virtual console is (slightly modified) VNC over a websocket

@littlefox @volpeon
*sigh*
OK, you wanted it:

AMI MegaRAC (the BMC web UI for servers) has this feature where they allow you to select a .iso image for a CD-ROM in the web console (next to the KVM/VNC viewer).

How did they implement the CD-ROM emulation?
They open a WebSockets connection to the BMC, emulate a SCSI CD-ROM drive in JavaScript (!) and send raw SCSI packets back&forth via WebSockets, which the BMC then forwards via internal USB to the host system.

@littlefox @volpeon
*sigh*
OK, you wanted it:

AMI MegaRAC (the BMC web UI for servers) has this feature where they allow you to select a .iso image for a CD-ROM in the web console (next to the KVM/VNC viewer).

How did they implement the CD-ROM emulation?
They open a WebSockets connection to the BMC, emulate a SCSI CD-ROM drive in JavaScript (!) and send raw SCSI packets back&forth via WebSockets, which the BMC then forwards via internal USB to the host system.

@littlefox @volpeon
*sigh*
OK, you wanted it:

AMI MegaRAC (the BMC web UI for servers) has this feature where they allow you to select a .iso image for a CD-ROM in the web console (next to the KVM/VNC viewer).

How did they implement the CD-ROM emulation?
They open a WebSockets connection to the BMC, emulate a SCSI CD-ROM drive in JavaScript (!) and send raw SCSI packets back&forth via WebSockets, which the BMC then forwards via internal USB to the host system.

@manawyrm @littlefox @volpeon not sure I fully understand, doesn't that mean the browser page with the ISO "upload" needs to stay open and active for the whole duration of what you're doing with the bootable image?

@funkylab @littlefox @volpeon Yes, that‘s right. It‘s being „streamed“ in real time from your browser, which also means that the speed is directly dependent on your latency to the server, because each sector read needs a command -> response interaction.

There wouldn‘t be any space anywhere for the BMC to store an entire ISO (not enough RAM or flash memory).

@manawyrm @littlefox @volpeon yeah I was wondering where images were stored, but assumed there must just be enough flash for that; I was wrong!

@funkylab @littlefox @volpeon some BMCs can also live stream images from HTTP, but that‘s an even more insane mechanism, where it generates HTTP requests on the fly for each sector (2048bytes) read from the CD.

Yes, one HTTP request per sector. It‘s a mini DDoS

@manawyrm @littlefox @volpeon well uefi specifies boot via HTTP https://uefi.org/specs/UEFI/2.11/24_Network_Protocols_SNP_PXE_BIS.html#http-boot ; there's an entirely (nah, let's go with homeopathically) reasonable world where the BMC acts as HTTP server, using as much of its own RAM as read cache as possible,to minimize that latency penalty (physical CD-ROM drives also benefit from locality, because seeking across half a disk is probably slower than awaiting replies from residential V.90 modems)