Re: [edk2-devel] [PATCH] MdeModulePkg/XhciDxe: Non-zero start/stop values in XhcGetElapsedTicks

["Laszlo Ersek" <lersek@redhat.com>]

On 11/1/23 02:12, Mike Maslenkin wrote:
> On Tue, Oct 31, 2023 at 7:52 PM Henz, Patrick <patrick.henz@hpe.com> wrote:
>>
>> REF:https://bugzilla.tianocore.org/show_bug.cgi?id=4578
>>
>> The implementation of XhcGetElapsedTicks did not account for
>> non-zero start and stop values for the performance counter
>> timer, potentially resulting in an incorrect elapsed tick
>> count getting returned to the caller. Account for non-zero
>> start and stop values when calculating the elapsed tick
>> count.
>>
>> Cc: Hao A Wu <hao.a.wu@intel.com>
>> Cc: Ray Ni <ray.ni@intel.com>
>> Signed-off-by: Patrick Henz <patrick.henz@hpe.com>
>> Reviewed-by:
>> ---
>>  MdeModulePkg/Bus/Pci/XhciDxe/Xhci.c | 4 ++--
>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/MdeModulePkg/Bus/Pci/XhciDxe/Xhci.c b/MdeModulePkg/Bus/Pci/XhciDxe/Xhci.c
>> index 7a2e32a9dd..6cb97b7452 100644
>> --- a/MdeModulePkg/Bus/Pci/XhciDxe/Xhci.c
>> +++ b/MdeModulePkg/Bus/Pci/XhciDxe/Xhci.c
>> @@ -2389,7 +2389,7 @@ XhcGetElapsedTicks (
>>      // Counter counts upwards, check for an overflow condition
>>      //
>>      if (*PreviousTick > CurrentTick) {
>> -      Delta = (mPerformanceCounterEndValue - *PreviousTick) + CurrentTick;
>> +      Delta = (CurrentTick - mPerformanceCounterStartValue) + (mPerformanceCounterEndValue - *PreviousTick);
>>      } else {
>>        Delta = CurrentTick - *PreviousTick;
>>      }
>> @@ -2398,7 +2398,7 @@ XhcGetElapsedTicks (
>>      // Counter counts downwards, check for an underflow condition
>>      //
>>      if (*PreviousTick < CurrentTick) {
>> -      Delta = (mPerformanceCounterStartValue - CurrentTick) + *PreviousTick;
>> +      Delta = (mPerformanceCounterStartValue - CurrentTick) + (*PreviousTick - mPerformanceCounterEndValue);
>>      } else {
>>        Delta = *PreviousTick - CurrentTick;
>>      }
>> --
>> 2.34.1
>>
>>
>>
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>>
> Hello, All
>
> Just curious why this patch was broken by google groups.
>
> Some patches to edk2 and edk2-redfish-client have unintended line
> breaks marked with "=",  additional "0D" and additional "3D" to "="
> Web shows https://edk2.groups.io/g/devel/message/110434 exactly as it
> saved by mailer.
> What do sender should setup to avoid this?

I recommend selecting base64 content-transfer-encoding, rather than
quode-printable. Base64 will ensure that the embedded CRLFs (which are
used in the edk2 source tree) survive intact, and also that "git-am" can
cleanly apply the patch (as saved from the mailing list).

Base64 is more robust than 8bit too. (If 8bit survived all mail servers
along the way, it would work fine as well.)

... According to my notes, git has always *ignored* the

[sendemail]
        transferEncoding = base64

stanza in my git config file. Which is why I have an alias around
git-send-email that open-codes

  git send-email --transfer-encoding=base64 ...

So that's what I recommend.

(BTW, our "BaseTools/Scripts/SetupGit.py" script sets
"sendemail.transferEncoding=8bit", but that is problematic for two
reasons: (1) git ignores it anyway, per my records mentioned above, (2)
8bit is inferior to base64 in practice, when it comes to CRLF integrity
across all email servers.)

... Side comment: I can apply quoted-printable-encoded patches as well,
from the list, but that's only because I manually transcode them to
8bit, before passing them to git-am. I use the following hairy script:

----------------------------
#!/bin/bash
set -e -u -C

TMPD=$(mktemp -d)
trap 'rm -f -r -- "$TMPD"' EXIT

cd "$TMPD"
tee input | dos2unix | csplit -s - '/^$/'
HEAD_LINES=$(wc -l < xx00)

head -n "$HEAD_LINES" input \
| sed -r 's/^(Content-Transfer-Encoding: )quoted-printable/\18bit/'

tail -n +$((HEAD_LINES + 1)) input \
| perl -p -e 'use MIME::QuotedPrint; $_=MIME::QuotedPrint::decode($_);' \
| unix2dos
----------------------------

(The perl command is from Paolo Bonzini.)

Summary: send your patches with

  git send-email --transfer-encoding=base64 ...

Laszlo



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