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authorEric Blake <eblake@redhat.com>2021-02-11 14:44:37 -0600
committerEric Blake <eblake@redhat.com>2021-03-08 13:36:37 -0600
commitf174cd3350c5e97db000e7383be974c66046b8f5 (patch)
tree01833a8fd59c747e40595918a2b82252b76ef734 /docs/system
parentcf923b783efd565787e9ab006fb5608bb2a7297b (diff)
downloadfocaccia-qemu-f174cd3350c5e97db000e7383be974c66046b8f5.tar.gz
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utils: Deprecate hex-with-suffix sizes
Supporting '0x20M' looks odd, particularly since we have a 'B' suffix
that is ambiguous for bytes, as well as a less-frequently-used 'E'
suffix for extremely large exibytes.  In practice, people using hex
inputs are specifying values in bytes (and would have written
0x2000000, or possibly relied on default_suffix in the case of
qemu_strtosz_MiB), and the use of scaling suffixes makes the most
sense for inputs in decimal (where the user would write 32M).  But
rather than outright dropping support for hex-with-suffix, let's
follow our deprecation policy.  Sadly, since qemu_strtosz() does not
have an Err** parameter, and plumbing that in would be a much larger
task, we instead go with just directly emitting the deprecation
warning to stderr.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20210211204438.1184395-4-eblake@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Diffstat (limited to 'docs/system')
-rw-r--r--docs/system/deprecated.rst8
1 files changed, 8 insertions, 0 deletions
diff --git a/docs/system/deprecated.rst b/docs/system/deprecated.rst
index cfabe69846..ecff6bf8c6 100644
--- a/docs/system/deprecated.rst
+++ b/docs/system/deprecated.rst
@@ -166,6 +166,14 @@ Using ``-M kernel-irqchip=off`` with x86 machine types that include a local
 APIC is deprecated.  The ``split`` setting is supported, as is using
 ``-M kernel-irqchip=off`` with the ISA PC machine type.
 
+hexadecimal sizes with scaling multipliers (since 6.0)
+''''''''''''''''''''''''''''''''''''''''''''''''''''''
+
+Input parameters that take a size value should only use a size suffix
+(such as 'k' or 'M') when the base is written in decimal, and not when
+the value is hexadecimal.  That is, '0x20M' is deprecated, and should
+be written either as '32M' or as '0x2000000'.
+
 QEMU Machine Protocol (QMP) commands
 ------------------------------------