Re: [Xen-devel] [RFC XEN PATCH v4 34/41] tools/libacpi: probe QEMU ACPI ROMs via fw_cfg interface

[Haozhong Zhang <haozhong.zhang@xxxxxxxxx>]

On 02/27/18 17:56 +0000, Anthony PERARD wrote:
> On Thu, Dec 07, 2017 at 06:10:23PM +0800, Haozhong Zhang wrote:
> > Probe following QEMU ACPI ROMs:
> >  * etc/acpi/rsdp:       QEMU RSDP, which is used to iterate other
> >                         QEMU ACPI tables in etc/acpi/tables
> > 
> >  * etc/acpi/tables:     other QEMU ACPI tables
> > 
> >  * etc/table-loader:    QEMU BIOSLinkerLoader ROM, which can be
> >                         executed to load QEMU ACPI tables
> > 
> >  * etc/acpi/nvdimm-mem: RAM which is used as NVDIMM ACPI DSM buffer,
> >                         the exact location will be allocated during
> >                         the execution of /etc/table-loader
> > 
> > Signed-off-by: Haozhong Zhang <haozhong.zhang@xxxxxxxxx>
> > ---
> 
> > diff --git a/tools/libacpi/qemu_loader.c b/tools/libacpi/qemu_loader.c
> > new file mode 100644
> > index 0000000000..c0ed3b0ad0
> > --- /dev/null
> > +++ b/tools/libacpi/qemu_loader.c
> > @@ -0,0 +1,82 @@
> > +/*
> > + * libacpi/qemu_loader.c
> > + *
> > + * Driver of QEMU BIOSLinkerLoader interface. The reference document
> > + * can be found at
> > + * https://github.com/qemu/qemu/blob/master/hw/acpi/bios-linker-loader.c.
> 
> That's only a mirror, the official QEMU tree is on git.qemu.org. So I
> think the URL should read:
> https://git.qemu.org/?p=qemu.git;a=blob;f=hw/acpi/bios-linker-loader.c;hb=HEAD

will fix the url

> 
> > + *
> > + * Copyright (C) 2017,  Intel Corporation
> > + *
> > + * This library is free software; you can redistribute it and/or
> > + * modify it under the terms of the GNU Lesser General Public
> > + * License, version 2.1, as published by the Free Software Foundation.
> > + *
> > + * This library is distributed in the hope that it will be useful,
> > + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> > + * Lesser General Public License for more details.
> > + *
> > + * You should have received a copy of the GNU Lesser General Public
> > + * License along with this library; If not, see 
> > <http://www.gnu.org/licenses/>.
> > + */
> > +
> > +#include LIBACPI_STDUTILS
> > +#include "libacpi.h"
> > +#include "qemu.h"
> > +
> > +struct rom {
> > +    struct fw_cfg_file file;
> > +    struct rom *next;
> > +};
> > +
> > +static struct rom *roms = NULL;
> > +static struct rom *bios_loader = NULL;
> > +
> > +static bool rom_needed(const char *file_name)
> > +{
> > +    return
> > +        !strncmp(file_name, "etc/acpi/rsdp", FW_CFG_FILE_PATH_MAX_LENGTH) 
> > ||
> > +        !strncmp(file_name, "etc/acpi/tables", 
> > FW_CFG_FILE_PATH_MAX_LENGTH) ||
> > +        !strncmp(file_name, "etc/table-loader", 
> > FW_CFG_FILE_PATH_MAX_LENGTH) ||
> > +        !strncmp(file_name, "etc/acpi/nvdimm-mem", 
> > FW_CFG_FILE_PATH_MAX_LENGTH);
> 
> Is it necessary to filter the "files" that are available via fw_cfg? Is
> there enough memory for hvmloader to just alocate the "struct rom" for
> every available files? Other solution might be to filter base on
> "etc/acpi/*" + "etc/table-loader".
>

The filter here is primarily to avoid loading unused roms in case that
their presence may have harmful side-effects (though I can't image what
side-effects could be).

Haozhong

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