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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 18:39:01 +0300 |
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 */
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