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Re: [Qemu-devel] [PATCH v5 3/8] fw_cfg: add vmcoreinfo file
From: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-devel] [PATCH v5 3/8] fw_cfg: add vmcoreinfo file |
Date: |
Fri, 8 Sep 2017 18:39:51 +0300 |
On Fri, Sep 08, 2017 at 06:39:01PM +0300, Michael S. Tsirkin wrote:
> On Mon, Aug 07, 2017 at 08:16:13PM +0200, Marc-André Lureau wrote:
> > diff --git a/docs/specs/fw_cfg.txt b/docs/specs/fw_cfg.txt
> > index 08c00bdf44..37d0f9f40a 100644
> > --- a/docs/specs/fw_cfg.txt
> > +++ b/docs/specs/fw_cfg.txt
> > @@ -136,6 +136,22 @@ struct FWCfgFile { /* an individual file
> > entry, 64 bytes total */
> > char name[56]; /* fw_cfg item name, NUL-terminated ascii */
> > };
> >
> > +=== etc/vmcoreinfo ===
> > +
> > +A guest may use this entry to add information details to qemu
> > +dumps. The entry gives location and size of an ELF note that is
> > +appended in qemu dumps.
> > +
> > +The entry is of 12 bytes with this format:
> > +
> > +struct FWCfgVMCoreInfo {
> > + uint64_t paddr; /* physical address of ELF note, LE */
> > + uint32_t size; /* size of ELF note region, LE */
> > +};
> > +
> > +The note format/class must be of the target bitness and the size must
> > +be less than 1Mb.
> > +
>
> I would say adding a format bitmap would make sense for future compatibility.
> How about:
>
> struct FWCfgVMCoreInfo {
> uint16_t host_format; /* Formats host supports. 0x1 LE - ELF note.
> Other bits - ignored. */
> uint16_t guest_format; /* Formats guest supplies. Must be 0x1 LE */
.. to set the ELF note info, or 0x0 to reset the device.
> uint32_t size; /* size of ELF note region, LE */
> uint64_t paddr; /* physical address of ELF note, LE */
> };
>
>
> > === All Other Data Items ===
> >
> > Please consult the QEMU source for the most up-to-date and authoritative
> > list
> > --
> > 2.14.0.1.geff633fa0