Hi Tony,
On Thu, 22 Feb 2018 11:58:10 -0800, Tony Luck wrote:
> When we first scan the SMBIOS table, save the size of the DIMM.
>
> Provide a function for other code (EDAC driver) to look up the size
> of a DIMM from its SMBIOS handle.
On the principle I'm OK with the idea. My comments on the
implementation details are inline below.
> Signed-off-by: Tony Luck <tony.luck@xxxxxxxxx>
> ---
> drivers/firmware/dmi_scan.c | 31 +++++++++++++++++++++++++++++++
> include/linux/dmi.h | 2 ++
> 2 files changed, 33 insertions(+)
>
> diff --git a/drivers/firmware/dmi_scan.c b/drivers/firmware/dmi_scan.c
> index e763e1484331..9947f1f6ef7b 100644
> --- a/drivers/firmware/dmi_scan.c
> +++ b/drivers/firmware/dmi_scan.c
> @@ -32,6 +32,7 @@ static char dmi_ids_string[128] __initdata;
> static struct dmi_memdev_info {
> const char *device;
> const char *bank;
> + u64 size;
A comment stating in which unit the size is stored would be appreciated.
> u16 handle;
> } *dmi_memdev;
> static int dmi_memdev_nr;
> @@ -386,6 +387,8 @@ static void __init save_mem_devices(const struct dmi_header *dm, void *v)
> {
> const char *d = (const char *)dm;
> static int nr;
> + u64 bytes;
> + u16 size;
>
> if (dm->type != DMI_ENTRY_MEM_DEVICE || dm->length < 0x12)
> return;
> @@ -396,6 +399,20 @@ static void __init save_mem_devices(const struct dmi_header *dm, void *v)
> dmi_memdev[nr].handle = get_unaligned(&dm->handle);
> dmi_memdev[nr].device = dmi_string(dm, d[0x10]);
> dmi_memdev[nr].bank = dmi_string(dm, d[0x11]);
> +
> + size = get_unaligned((u16 *)&d[0xC]);
> + if (size == 0)
> + bytes = 0;
> + else if (size == 0xffff)
> + bytes = ~0ul;
Should this not be ~0ull? On 32-bit systems ~0ul would be 0xffffffff not
0xffffffffffffffff.
Also it would be nice to document somewhere that 0 means memory module
not installed and all fs means size is unknown.
> + else if (size & 0x8000)
> + bytes = (u64)(size & 0x7fff) << 10;
> + else if (size != 0x7fff)
> + bytes = (u64)size << 20;
> + else
> + bytes = (u64)get_unaligned((u32 *)&d[0x1C]) << 20;
> +
> + dmi_memdev[nr].size = bytes;
I'm curious, do you really need to know the amount of memory to the
byte? The SMBIOS specification itself does not support granularity
under 1 kB. I would be very surprised if any machine running Linux
today has memory modules under 1 MB. If storing in MB you wouldn't need
a u64...
> nr++;
> }
>
> @@ -1065,3 +1082,17 @@ void dmi_memdev_name(u16 handle, const char **bank, const char **device)
> }
> }
> EXPORT_SYMBOL_GPL(dmi_memdev_name);
> +
> +u64 dmi_memdev_size(u16 handle)
> +{
> + int n;
> +
> + if (dmi_memdev) {
> + for (n = 0; n < dmi_memdev_nr; n++) {
> + if (handle == dmi_memdev[n].handle)
> + return dmi_memdev[n].size;
> + }
> + }
> + return ~0ul;
~0ull?
> +}
> +EXPORT_SYMBOL_GPL(dmi_memdev_size);
> diff --git a/include/linux/dmi.h b/include/linux/dmi.h
> index 46e151172d95..7f5929123b69 100644
> --- a/include/linux/dmi.h
> +++ b/include/linux/dmi.h
> @@ -113,6 +113,7 @@ extern int dmi_walk(void (*decode)(const struct dmi_header *, void *),
> void *private_data);
> extern bool dmi_match(enum dmi_field f, const char *str);
> extern void dmi_memdev_name(u16 handle, const char **bank, const char **device);
> +extern u64 dmi_memdev_size(u16 handle);
>
> #else
>
> @@ -142,6 +143,7 @@ static inline bool dmi_match(enum dmi_field f, const char *str)
> { return false; }
> static inline void dmi_memdev_name(u16 handle, const char **bank,
> const char **device) { }
> +static inline u64 dmi_memdev_size(u16 handle) { return ~0ul; }
~0ull?
> static inline const struct dmi_system_id *
> dmi_first_match(const struct dmi_system_id *list) { return NULL; }
>
--
Jean Delvare
SUSE L3 Support
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