mbox series

[Xen-devel,v3,0/2,FIX-for-4.10] Fix SBSA UART emulation

Message ID 20171024170922.17207-1-andre.przywara@linaro.org
Headers show
Series Fix SBSA UART emulation | expand


Andre Przywara Oct. 24, 2017, 5:09 p.m. UTC

the SBSA UART emulation as in the staging tree right now has two problems:
- The pl011 earlycon output from a guest is very slow (think: WarGames).
  This is due to every character being synchronously handed over to Xen.
  This is not very critical (just slow), but it increases boot times
  of guests using an SBSA UART.
- The normal SBSA console in a guest can lose characters when outputting
  a bigger number of characters in quick succession, as demonstrated by
  running a simple "find /" in a guest on a virtual SBSA console.
  As we actually miss characters, I consider this bug more severe.

This series fixes both problems, more technial details on how can be
found in the respective commit messages.

I would like to see both patches merged into 4.10 still, as:
- They fix real bugs.
- They are not too intrusive, touching only the vpl011.c file with the
  emulation code in xen/arch/arm.
- The SBSA UART is a new feature, so there is no possible regression
  compared to the previous release.


Bhupinder Thakur (2):
  arm/xen: vpl011: Fix the slow early console SBSA UART output
  arm/xen: vpl011: Fix SBSA UART interrupt assertion

 xen/arch/arm/vpl011.c        | 136 +++++++++++++++++++++++++++++++------------
 xen/include/asm-arm/vpl011.h |   2 +
 2 files changed, 102 insertions(+), 36 deletions(-)