From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:58298) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gSQQs-0000hU-Qx for qemu-devel@nongnu.org; Thu, 29 Nov 2018 12:49:01 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gSQQm-0006sR-0i for qemu-devel@nongnu.org; Thu, 29 Nov 2018 12:48:56 -0500 Date: Thu, 29 Nov 2018 18:48:01 +0100 From: Samuel Ortiz Message-ID: <20181129174801.GA4195@caravaggio> References: <20181129132428.333-1-sameo@linux.intel.com> <20181129132428.333-7-sameo@linux.intel.com> <20181129144243.so22d2igis7a24xp@kamzik.brq.redhat.com> <20181129145942.GB4691@caravaggio> <20181129150947.hqsnpf653vs53uci@kamzik.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181129150947.hqsnpf653vs53uci@kamzik.brq.redhat.com> Subject: Re: [Qemu-devel] [PATCH v2 6/8] hw: arm: Support both legacy and current RSDP build List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Andrew Jones Cc: qemu-devel@nongnu.org, Laurent Vivier , Peter Maydell , Thomas Huth , Eduardo Habkost , Ben Warren , "Michael S. Tsirkin" , Shannon Zhao , qemu-arm@nongnu.org, Igor Mammedov , Paolo Bonzini , Richard Henderson On Thu, Nov 29, 2018 at 04:09:47PM +0100, Andrew Jones wrote: > On Thu, Nov 29, 2018 at 03:59:42PM +0100, Samuel Ortiz wrote: > > On Thu, Nov 29, 2018 at 03:42:43PM +0100, Andrew Jones wrote: > > > On Thu, Nov 29, 2018 at 02:24:26PM +0100, Samuel Ortiz wrote: > > > > We add the ability to build legacy or current RSDP tables, based on the > > > > AcpiRsdpData revision field passed to build_rsdp(). > > > > Although arm/virt only uses RSDP v2, adding that capability to > > > > build_rsdp will allow us to share the RSDP build code between ARM and x86. > > > > > > > > Signed-off-by: Samuel Ortiz > > > > --- > > > > hw/arm/virt-acpi-build.c | 37 ++++++++++++++++++++++++++----------- > > > > 1 file changed, 26 insertions(+), 11 deletions(-) > > > > > > > > diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c > > > > index 4782aea4fe..e1338b6f5a 100644 > > > > --- a/hw/arm/virt-acpi-build.c > > > > +++ b/hw/arm/virt-acpi-build.c > > > > @@ -378,23 +378,38 @@ build_rsdp(GArray *tbl, BIOSLinker *linker, AcpiRsdpData *rsdp_data) > > > > g_array_append_vals(tbl, rsdp_data->oem_id, 6); /* OEMID */ > > > > build_append_int_noprefix(tbl, rsdp_data->revision, 1); /* Revision */ > > > > build_append_int_noprefix(tbl, 0, 4); /* RsdtAddress */ > > > > - build_append_int_noprefix(tbl, 36, 4); /* Length */ > > > > - > > > > - /* XSDT address to be filled by guest linker */ > > > > - build_append_int_noprefix(tbl, 0, 8); /* XsdtAddress */ > > > > - bios_linker_loader_add_pointer(linker, ACPI_BUILD_RSDP_FILE, > > > > - 24, 8, > > > > - ACPI_BUILD_TABLE_FILE, > > > > - *rsdp_data->xsdt_tbl_offset); > > > > - > > > > - build_append_int_noprefix(tbl, 0, 1); /* Extended Checksum */ > > > > - build_append_int_noprefix(tbl, 0, 3); /* Reserved */ > > > > + if (rsdp_data->rsdt_tbl_offset) { > > > > > > I see why a pointer was used now. Using a pointer ensures a zero > > > offset won't fail this test. However the test could be replaced with > > > rsdp_data->revision == 0. > > > > > > > + /* RSDT address to be filled by guest linker */ > > > > + bios_linker_loader_add_pointer(linker, > > > > + ACPI_BUILD_RSDP_FILE, 16, 4, > > > > + ACPI_BUILD_TABLE_FILE, > > > > + *rsdp_data->rsdt_tbl_offset); > > > > + } > > > > > > > > /* Checksum to be filled by guest linker */ > > > > bios_linker_loader_add_checksum(linker, ACPI_BUILD_RSDP_FILE, > > > > 0, 20, /* ACPI rev 1.0 RSDP size */ > > > > 8); > > > > > > > > + if (rsdp_data->revision == 0) { > > > > + /* ACPI 1.0 RSDP, we're done */ > > > > + return; > > > > + } > > > > + > > > > + /* The RSDP revision is 2 and later, we must have an XSDT pointer */ > > > > + g_assert(rsdp_data->xsdt_tbl_offset != NULL); > > > > > > So here's the justification for the pointers. We sanity check the callers. > > We could sanity check the callers without pointers as well, I don't > > think there's a strong advantage for pointers here, except consistence. > > > > > > > We're missing the (rsdp_data->revision == 0 && rsdp_data->rsdt_tbl_offset) > > > sanity check though. > > I think there's nothing preventing a caller to include both rsdt and > > xsdt if it wants to be able to run on both < 2.0 and 2.0+ platforms with > > the same table. So if rsdt is set we should add it, regardless of the revision. > > True, but if revision is zero, then we *must* have it. Otherwise we'll > silently return from this function with neither an rsdt nor xsdt linked. Correct, thanks. With v3 I'm adding a small piece of code at the start of build_rsdp() that checks for valid rsdt and xsdt pointers (for rev 0 and 2, respectively). Cheers, Samuel.