Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit c56d63e5 authored by David Pursell's avatar David Pursell
Browse files

fastboot: update getvar documentation. 

The protocol doc states that calling `fastboot getvar` for an unknown
variable should return an empty OKAY message, but in reality modern
devices return a FAIL response in this case (tested with marlin and
shamu).

Additionally, some A/B logic in fastboot expects a FAIL response for
unknown variables in order to function properly.

This CL changes the documentation to match reality.

Bug: http://b/33756193
Test: none
Change-Id: I41f7c80585be73e60ca0ac216787596c4d60a1d5
parent 3d6d5b10

fastboot/fastboot_protocol.txt

+12 −5
Original line number Diff line number Diff line
@@ -78,7 +78,7 @@ Client: "OKAY0.4" return version "0.4" 


Host:    "getvar:nonexistant"    request some undefined variable



Client:  "OKAY"                  return value ""

Client:  "FAILUnknown variable"  getvar failure; see getvar details below



Host:    "download:00001234"     request to send 0x1234 bytes of data
@@ -113,7 +113,14 @@ Command Reference 


 "getvar:%s"           Read a config/version variable from the bootloader.

                       The variable contents will be returned after the

                       OKAY response.

                       OKAY response. If the variable is unknown, the bootloader

                       should return a FAIL response, optionally with an error

                       message.



                       Previous versions of this document indicated that getvar

                       should return an empty OKAY response for unknown

                       variables, so older devices might exhibit this behavior,

                       but new implementations should return FAIL instead.



 "download:%08x"       Write data to memory which will be later used

                       by "boot", "ramdisk", "flash", etc.  The client
@@ -215,7 +222,7 @@ Device FB01 
Host    [0x00][0x00][0x00][0x00][0x00][0x00][0x00][0x0E]getvar:version

Device  [0x00][0x00][0x00][0x00][0x00][0x00][0x00][0x07]OKAY0.4

Host    [0x00][0x00][0x00][0x00][0x00][0x00][0x00][0x0B]getvar:none

Device  [0x00][0x00][0x00][0x00][0x00][0x00][0x00][0x04]OKAY

Device  [0x00][0x00][0x00][0x00][0x00][0x00][0x00][0x14]FAILUnknown variable

Host    <disconnect>
@@ -364,10 +371,10 @@ ID Flags SeqH SeqL Data ID Flags SeqH SeqL Data 
                                        0x03  0x00  0x00  0x01

0x03  0x00  0x00  0x02

                                        0x03  0x00  0x00  0x02  OKAY0.4

0x03  0x00  0x00  0x03  getvar:foo

0x03  0x00  0x00  0x03  getvar:none

                                        0x03  0x00  0x00  0x03

0x03  0x00  0x00  0x04

                                        0x03  0x00  0x00  0x04  OKAY

                                        0x03  0x00  0x00  0x04  FAILUnknown var



----------------------------------------------------------------------

[fastboot "INFO" responses, S = 0x0000]