On 12/02/16 17:02, Anthony PERARD wrote: > On Thu, Dec 01, 2016 at 07:43:24PM +0100, Laszlo Ersek wrote: >> On 12/01/16 16:28, Anthony PERARD wrote: >>> Hi, >>> >>> That might be only with the Xen part of OVMF but now that the GCC5 >>> toolchains is used with my gcc (6.2.1 20160830, Arch Linux), OVMF fail >>> to boot in Xen guests. >>> > [...] >>> >>> Removing the gcc option -flto in only the XenBusDxe module makes OVMF >>> boot. >>> >>> While trying to debug that, I've added some debug prints (in this module >>> and in XenPvBlkDxe), and the exception could change and become a "page >>> fault" instead, or even an assert failure in the PrintLib, that was the >>> ASSERT(Buffer != NULL) at I think >>> MdePkg/Library/BasePrintLib/PrintLibInternal.c:366 >>> >>> Adding EFIAPI to internal functions in XenBusDxe makes things work >>> again. My guest is that gcc would bypass (optimise) an exported >>> functions and call directly an internal one but without reordering the >>> arguments (EFIAPI vs nothing). >>> >>> Does that make sense? >> >> If "-b NOOPT" works for you, I'd prefer that as a temporary solution >> (until the root cause is found and addressed) to the XenBusDxe patches. > > That works, using GCC49 (with gcc 6.2.1) works as well. > >> Hrpmf, wait a second, I do see something interesting: in this series you >> *are* modifying APIs declared in a library class header (namely >> "OvmfPkg/Include/Library/XenHypercallLib.h"). Such functions (public >> libraries) *are* required to specify EFIAPI. >> >> What happens if you apply patch #1 only? > > With only XenHypercallLib changes, the error is the same. > > But I did find the minimum change needed, it envolve a function with a > VA_LIST as argument. > > With only the following patch, OVMF works again. > > diff --git a/OvmfPkg/XenBusDxe/XenStore.c b/OvmfPkg/XenBusDxe/XenStore.c > index 1666c4b..85b0956 100644 > --- a/OvmfPkg/XenBusDxe/XenStore.c > +++ b/OvmfPkg/XenBusDxe/XenStore.c > @@ -1307,6 +1307,7 @@ XenStoreTransactionEnd ( > } > > XENSTORE_STATUS > +EFIAPI > XenStoreVSPrint ( > IN CONST XENSTORE_TRANSACTION *Transaction, > IN CONST CHAR8 *DirectoryPath, > diff --git a/OvmfPkg/XenBusDxe/XenStore.h b/OvmfPkg/XenBusDxe/XenStore.h > index c9d4c65..33bb647 100644 > --- a/OvmfPkg/XenBusDxe/XenStore.h > +++ b/OvmfPkg/XenBusDxe/XenStore.h > @@ -209,6 +209,7 @@ XenStoreSPrint ( > indicating the type of write failure. > **/ > XENSTORE_STATUS > +EFIAPI > XenStoreVSPrint ( > IN CONST XENSTORE_TRANSACTION *Transaction, > IN CONST CHAR8 *DirectoryPath, > IN CONST CHAR8 *Node, > IN CONST CHAR8 *FormatString, > IN VA_LIST Marker > ); > > > I think the exception happen when this function is called via > XENBUS_PROTOCOL->XsPrintf() from XenPvBlockFrontInitialization() in > OvmfPkg/XenPvBlkDxe/BlockFront.c >
It used to be a known requirement / limitation that all functions with variable argument lists had to be EFIAPI, regardless of cross-module use. However, commit 48d5f9a551a93acb45f272dda879b0ab5a504e36 changed that, and varargs should "just work" now. I suspect this is a __builtin_ms_va_* regression in gcc-6. Thank you for narrowing it down. It might make sense to report a bug in the upstream gcc tracker. ... Oh wow, this is a known gcc bug! See: https://lists.01.org/pipermail/edk2-devel/2016-August/001018.html Upstream gcc BZ <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70955> was apparently solved for "Target Milestone: 6.3" (your version is 6.2.1). So we'll either need a GCC6 toolchain in BaseTools that drops -flto, in order to work around this gcc issue, or we'll have to ask gcc-6 users to use at least gcc-6.3. Oh wait, gcc-6.3 hasn't been released yet. We need the BaseTools workaround then. Thanks! Laszlo _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel
