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2d441ca9cd
The Linux persistent store (pstore) feature serves, among other things, for saving the trailing portion of the dmesg in case of a kernel oops. One backend for the pstore facility is "efivars", ie. non-volatile UEFI variables. Linux splits the tail of the dmesg that is to be dumped in 1KB chunks, and tries to save each chunk as a specially (and differently) named non-volatile variable. The 1KB chunk size accounts for the variable data only; Linux expects this size to be available per variable *without* accounting for the variable name or any firmware-internal overhead. For non-authenticated (ie. non-secure-boot) variables, OvmfPkg currently sets the per-variable limit to 0x400 (1KB) through PcdMaxVariableSize. However this PCD determines the size *before* subtracting the internal overhead (which is sizeof(VARIABLE_HEADER) == 0x20 bytes for non-authenticated variables, see "MdeModulePkg/Include/Guid/VariableFormat.h"), and also before subtracting the given variable's UCS-2 encoded name (including the trailing 0x0000). Linux maximizes these special variable names in DUMP_NAME_LEN==52 code points (including the trailing NUL). Hence we must provide at least 0x020 == sizeof(VARIABLE_HEADER), for the internal overhead 0x068 == 2 * 52, for the UCS-2 encoded name, including trailing 0x0000 0x400 for the variable body ----- 0x488 == 1160 bytes in PcdMaxVariableSize, so that Linux's efivars-backed pstore can work even on non-secure-boot builds of OVMF. However, as PcdMaxVariableSize=0x2000 has proven reasonable when secure boot is enabled, it should also be okay when secure boot is disabled; so for simplicity's sake set PcdMaxVariableSize to 0x2000 unconditionally. Tested-by: Seiji Aguchi <seiji.aguchi@hds.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Reviewed-by: Jordan Justen <jordan.l.justen@intel.com> git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@15142 6f19259b-4bc3-4df7-8a09-765794883524 |
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| AppPkg | ||
| ArmPkg | ||
| ArmPlatformPkg | ||
| BaseTools | ||
| BeagleBoardPkg | ||
| Conf | ||
| CryptoPkg | ||
| DuetPkg | ||
| EdkCompatibilityPkg | ||
| EdkShellBinPkg | ||
| EdkShellPkg | ||
| EmbeddedPkg | ||
| EmulatorPkg | ||
| FatBinPkg | ||
| IntelFrameworkModulePkg | ||
| IntelFrameworkPkg | ||
| MdeModulePkg | ||
| MdePkg | ||
| NetworkPkg | ||
| Nt32Pkg | ||
| Omap35xxPkg | ||
| OptionRomPkg | ||
| OvmfPkg | ||
| PcAtChipsetPkg | ||
| PerformancePkg | ||
| SecurityPkg | ||
| ShellBinPkg | ||
| ShellPkg | ||
| SourceLevelDebugPkg | ||
| StdLib | ||
| StdLibPrivateInternalFiles | ||
| UefiCpuPkg | ||
| UnixPkg | ||
| BuildNotes2.txt | ||
| edksetup.bat | ||
| edksetup.sh | ||