[Bug 1508893] Re: TFTP timeout when booting from grub that was PXE loaded

[dann frazier]

** Description changed:

- This issue was discovered  with Ubuntu Wily (15.10) on a currently in
- development ARM64 HW.
+ [Impact]
+ PXE booting of UEFI systems is very slow, to the point that some systems timeout.
  
- When loading kernel via tftp in grub on this hardware, the system stops
- receiving new packets (times out )  after receiving initial few tens of
- tftp data packets , which then causes kernel load failure.
+ [Test Case]
+ PXE boot a UEFI-based system (d-i or MAAS) and monitor the time it takes for GRUB to download the kernel/initrd. tcpdump will show TFTP timeouts, and it can take on the order of minutes to begin running the kernel.
  
- Running tcpdump before loading kernel in grub menu shows timeouts
- occurring,  as captured in the below log  :
- 
-       http://kernel.ubuntu.com/~ming/grub/apm.tcpdump
- 
- Following are the  detailed reproduction steps :
- 
- 1) setup PXE boot entry in UEFI(no any parameter to grub)
- 2) build one grub from upstream (and/or Wily)  and put it in PXE&TFTP server
- 3) setup grub config, suppose the shape is like below:
-      menuentry 'Install for arm64' {
-           linux /ubuntu-installer/arm64/Image --- console=ttyS0,115200
-           initrd /ubuntu-installer/arm64/initrd.gz
-     }
- 4) start PXE booting in UEFI
- 5) grub prompt is coming
- 6) select 'Install for arm64' menu item and press 'enter' to start
- loading kernel
- 7) then hangs inside loading kernel
+ [Regression Risk]
+ The fix is restricted to UEFI-based systems. For those systems, it could lead to a regression if Managed Network Protocol is required to remain active while GRUB is performing the network boot.

** Also affects: grub2 (Ubuntu Vivid)
   Importance: Undecided
       Status: New

** Also affects: grub2 (Ubuntu Wily)
   Importance: Undecided
       Status: New

** Also affects: grub2 (Ubuntu Trusty)
   Importance: Undecided
       Status: New

** Changed in: grub2 (Ubuntu Wily)
     Assignee: (unassigned) => dann frazier (dannf)

** Changed in: grub2 (Ubuntu Vivid)
     Assignee: (unassigned) => dann frazier (dannf)

** Changed in: grub2 (Ubuntu Trusty)
     Assignee: (unassigned) => dann frazier (dannf)

** Changed in: grub2 (Ubuntu)
   Importance: Undecided => High

** Changed in: grub2 (Ubuntu Trusty)
   Importance: Undecided => High

** Changed in: grub2 (Ubuntu Vivid)
   Importance: Undecided => High

** Changed in: grub2 (Ubuntu Wily)
   Importance: Undecided => High

** Changed in: grub2 (Ubuntu Trusty)
       Status: New => In Progress

** Changed in: grub2 (Ubuntu Wily)
       Status: New => In Progress

** Changed in: grub2 (Ubuntu Vivid)
       Status: New => In Progress

** Changed in: grub2 (Ubuntu)
       Status: Confirmed => In Progress

** Changed in: grub2 (Ubuntu)
     Assignee: (unassigned) => dann frazier (dannf)

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https://bugs.launchpad.net/bugs/1508893

Title:
  TFTP timeout when booting from grub that was  PXE loaded

Status in grub2 package in Ubuntu:
  In Progress
Status in grub2 source package in Trusty:
  In Progress
Status in grub2 source package in Vivid:
  In Progress
Status in grub2 source package in Wily:
  In Progress

Bug description:
  [Impact]
  PXE booting of UEFI systems is very slow, to the point that some systems timeout.

  [Test Case]
  PXE boot a UEFI-based system (d-i or MAAS) and monitor the time it takes for GRUB to download the kernel/initrd. tcpdump will show TFTP timeouts, and it can take on the order of minutes to begin running the kernel.

  [Regression Risk]
  The fix is restricted to UEFI-based systems. For those systems, it could lead to a regression if Managed Network Protocol is required to remain active while GRUB is performing the network boot.

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