On Thu, 15 Apr 2021 at 21:22, Jeremy Linton <jeremy.lin...@arm.com> wrote: > > Under normal circumstances GenetSimpleNetworkTransmit won't be > called unless the rest of the network stack detects the link is > up. So, during normal operation when the adapter is initialized > the link naturally transitions to link up, and then is ready for > activity later in the boot sequence. If that hasn't happened by > the time PXE runs then it will itself wait for the link. > > OTOH, the normal distro PXE sequence involves PXE loading shim > which in turn loads grub, which tries to read machine specific > configs, modules, and grub.cfg in order to prepare the boot menu. > Then, once a grub selection is picked, it might try to load the > kernel+initrd. > > In this sequence the network stack is shutdown and restarted > multiple times. Grub though, starts up, notices its been network > booted, reads saved network parameters and immediately tries to > transmit data assuming the link is still up. > > When that happens grub will print "couldn't send network packet" > and if that lasts long enough it fails to load grub.cfg and the > user gets dropped to the grub prompt because no one in the path > bothers to assure the link state has transitioned back up. >
This is an excellent problem description. Could we dedicate a couple of paragraphs to the solution as well? Especially given that 'wait for random # of seconds' seems to be the taken approach here, which seems a bit sloppy to me, given that we should be able to detect whether the link is up, no? > For reference: https://github.com/pftf/RPi4/issues/113 > > Signed-off-by: Jeremy Linton <jeremy.lin...@arm.com> > --- > .../Drivers/Net/BcmGenetDxe/SimpleNetwork.c | 24 > ++++++++++++++++++++-- > 1 file changed, 22 insertions(+), 2 deletions(-) > > diff --git a/Silicon/Broadcom/Drivers/Net/BcmGenetDxe/SimpleNetwork.c > b/Silicon/Broadcom/Drivers/Net/BcmGenetDxe/SimpleNetwork.c > index 1bda18f157..29c76d8495 100644 > --- a/Silicon/Broadcom/Drivers/Net/BcmGenetDxe/SimpleNetwork.c > +++ b/Silicon/Broadcom/Drivers/Net/BcmGenetDxe/SimpleNetwork.c > @@ -13,6 +13,7 @@ > #include <Library/DebugLib.h> > #include <Library/DmaLib.h> > #include <Library/NetLib.h> > +#include <Library/UefiBootServicesTableLib.h> > #include <Protocol/SimpleNetwork.h> > > #include "BcmGenetDxe.h" > @@ -590,9 +591,28 @@ GenetSimpleNetworkTransmit ( > > if (!Genet->SnpMode.MediaPresent) { > // > - // Don't bother transmitting if there's no link. > + // We should only really get here if the link was up > + // and is now down due to a stop/shutdown sequence, and > + // the app (grub) doesn't bother to check link state > + // because it was up a moment before. > + // Lets wait a bit for the link to resume, rather than > + // failing to send. In the case of grub it works either way > + // but we can't be sure that is universally true, and > + // hanging for a couple seconds is nicer than a screen of > + // grub send failure messages. > // > - return EFI_NOT_READY; > + int retries = 1000; > + DEBUG ((DEBUG_INFO, "%a: Waiting 10s for link\n", __FUNCTION__)); > + do { > + gBS->Stall (10000); > + Status = GenericPhyUpdateConfig (&Genet->Phy); > + } while (EFI_ERROR (Status) && retries--); > + if (EFI_ERROR (Status)) { > + DEBUG ((DEBUG_ERROR, "%a: no link\n", __FUNCTION__)); > + return EFI_NOT_READY; > + } else { > + Genet->SnpMode.MediaPresent = TRUE; > + } > } > > if (HeaderSize != 0) { > -- > 2.13.7 > > > > > > -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#74902): https://edk2.groups.io/g/devel/message/74902 Mute This Topic: https://groups.io/mt/82125863/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
